http://www.physicsbook.gatech.edu/api.php?action=feedcontributions&feedformat=atom&user=Brainmurphy 2026-04-04T06:47:57Z User contributions MediaWiki 1.42.7 http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=15365 2015-12-05T20:43:59Z

<p>Brainmurphy: </p> <hr /> <div>The phenomenon of an electric field causing air to ionize such that the air emits light and sound is known as a spark. Sparks occur between two opposing charges, where the electric field between them is strong enough to cause the air molecules to split from their normally stable state, into positive and negative ions that can conduct current. <br /> <br /> ==The Physical Model==<br /> At a high level of abstraction, the occurrence of a spark is marked by three phases: the ionization of air particles, the propagation of the electric field in the air gap, and the neutralization of charges due to cancellation. These are no finite boundaries between these phases, although there is a general order to them, despite how quickly a spark occurs. <br /> ===Ionization of Air===<br /> In air, there is always some chance occurrence of ionized particles. However, air molecules (most notably Nitrogen and Oxygen) are very stable, so these ions do not make up a significant portion of all air molecules in our atmosphere. These stable molecules require a relatively large amount of energy to separate them from their electrons. Typically, collisions between air particles do not impart enough energy to ionize them -- separate them from some of their electrons.<br /> <br /> However, in the presence of a strong electric field, chance ions in the accelerate to very high speeds, gaining relatively large amounts of kinetic energy. In a strong enough electric field, these ions gain enough Kinetic energy to break apart air molecules when upon collision. The separation of the electrons from these air molecules creates two more ions: one negative (the electron) and one positive (the N2+ or O2+)<br /> ===Propagation of the Electric Field===<br /> Because electric fields are strongest near each of the two opposite charges, the chain reaction of ionization starts there. The new ions created through collisions with the ions accelerated by the electric field also accelerate due to the electric field. These new ions can then cause more air particles to ionize by striking them at high speeds. <br /> <br /> [[File:Sparks in the air 1371.jpg]] [http://www.nuffieldfoundation.org/practical-physics/sparks-air]The single ball causes multiple balls to &quot;ionize&quot;, which, in turn, cause more balls to roll down the ramp.<br /> <br /> The negatively charged ions move towards the positively charged object that started the spark, and the positively charged ions move towards the negatively charged object. As this happens, the charge distribution in the air between the two charged objects changes. Before the spark began, the electric field emanated from the two charged objects. As ions begin to form, the electric field also emanates in part from the ionized air. This causes the electric field between the two charged object to become more uniform, much like what occurs in a wire when a circuit is closed.<br /> Eventually, the chain reactions coming from each charged object meet in the middle, and the &quot;circuit&quot; is complete.<br /> ===Neutralization of Charges===<br /> The molecules of the air are now sufficiently ionized to carry a current. The electrons in the gap move relatively rapidly toward the positively charged object, while the positive ions move very slowly towards the negatively charged object, due to the differences in their masses. As the ions hit the charged surfaces to which they are attracted, they combine with oppositely charged particles on that object's surface. When this happens, the charge on each object diminishes due to the cancellation of fields. Soon, there is no longer enough charge on the objects to accelerate the ions enough to maintain an ionized air gap.<br /> As the charged particles move through, the air, they are constantly recombining with other ions in the process of random motion, before being again knocked apart by an accelerated charge. Sparks produce light because when molecules recombine, they move to a lower energy state, and emit the difference in energy as a photon. These continual reactions produce a lot of heat, which cases the air gap to rapidly expand and make the sound we hear when a spark occurs.<br /> ==A Mathematical Model==<br /> <br /> Let's run through a mathematical model of the situation to make sure that the numbers match up with our observations.<br /> How much of an electric field is required to accelerate the electrons enough to cause a chain reaction? At ground level, the average distance an air particle can travel before it makes contact with another is &lt;math&gt;1E-6m&lt;/math&gt;[http://physics.bu.edu/~redner/211-sp06/class-macro-micro/kinetic_meanfreepath.html]. This is known as the mean free path. Over this small of a distance, we can assume that the electric field will be roughly uniform. <br /> If we know that the average ionization energy for an air molecule is roughly &lt;math&gt;2E-18J&lt;/math&gt;[http://www.webelements.com/], then we can calculate what electric field magnitude will be necessary to cause a spark.<br /> <br /> &lt;math&gt;E |\!-\!e|&lt;/math&gt; constitutes the force applied to a free electron by the electric field, so<br /> <br /> &lt;math&gt;E e d&lt;/math&gt; must be the kinetic energy imparted to the electron over the mean free path, where &lt;math&gt;d&lt;/math&gt; is the mean free path.<br /> <br /> &lt;math&gt;E e d = K&lt;/math&gt;<br /> <br /> &lt;math&gt;E = {\frac{K}{ed}}&lt;/math&gt;<br /> <br /> &lt;math&gt;E = {\frac{(2E-18J)}{(1.6E-19C)(1E-6m)}}&lt;/math&gt;<br /> <br /> &lt;math&gt;E = 1.2E7{\frac{N}{C}}&lt;/math&gt;<br /> <br /> The experimentally observed value for &lt;math&gt;E&lt;/math&gt; is &lt;math&gt;3E6&lt;/math&gt;<br /> <br /> Should our answer be regarded as accurate? Knowing that air molecules, on average, already carry some kinetic energy before being stricken by accelerated ions, and that some of the ions will travel a much longer distance than the mean free path before hitting an air molecule, it is not surprising that our simplified calculation overestimates the amount of field required to cause a spark.<br /> <br /> ==History==<br /> Although it is well known that the greeks were aware of the phenomenon of electrical sparks, Leibniz formalized his observations of electric sparks in 1671. In 1716, Newton observes &quot;miniature sheet lightning&quot;. Franklin makes similar observations. In 1729, Gray discovers the conductivity of metals. In 1745, Haller reports that lightning tends to travel along metal objects, just like sparks. In 1749 Ben Franklin formalizes his idea for the experiment that would contribute his description of electricity, and in 1750 he suggests the idea for the lightning rod.<br /> ==Connectedness==<br /> [https://en.wikipedia.org/wiki/Lightning]Lightning is essentially a large spark between the earth's surface and the surface of a cloud.<br /> [https://en.wikipedia.org/wiki/Plasma_(physics)}Ionized air is also known as plasma, which most notably occurs in the sun.<br /> ==References==<br /> [http://www.nuffieldfoundation.org/practical-physics/sparks-air] Nuffield Foundation: ''Sparks In Air''<br /> <br /> [http://www.physics.csbsju.edu/370/jcalvert/dischg.htm.html] Saint Benedict Saint John's University: Electrical Discharges<br /> <br /> [http://link.springer.com/article/10.1007%2FBF02017730] N. Kyzhanovsky: Mapping the History of Electricity<br /> <br /> ==Category==<br /> [[Fields]]</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=File:Sparks_in_the_air_1371.jpg&diff=15340 2015-12-05T20:39:48Z

<p>Brainmurphy: model of an electron avalanche</p> <hr /> <div>model of an electron avalanche</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=15270 2015-12-05T20:30:43Z

<p>Brainmurphy: </p> <hr /> <div>The phenomenon of an electric field causing air to ionize such that the air emits light and sound is known as a spark. Sparks occur between two opposing charges, where the electric field between them is strong enough to cause the air molecules to split from their normally stable state, into positive and negative ions that can conduct current. <br /> <br /> ==The Physical Model==<br /> At a high level of abstraction, the occurrence of a spark is marked by three phases: the ionization of air particles, the propagation of the electric field in the air gap, and the neutralization of charges due to cancellation. These are no finite boundaries between these phases, although there is a general order to them, despite how quickly a spark occurs. <br /> ===Ionization of Air===<br /> In air, there is always some chance occurrence of ionized particles. However, air molecules (most notably Nitrogen and Oxygen) are very stable, so these ions do not make up a significant portion of all air molecules in our atmosphere. These stable molecules require a relatively large amount of energy to separate them from their electrons. Typically, collisions between air particles do not impart enough energy to ionize them -- separate them from some of their electrons.<br /> <br /> However, in the presence of a strong electric field, chance ions in the accelerate to very high speeds, gaining relatively large amounts of kinetic energy. In a strong enough electric field, these ions gain enough Kinetic energy to break apart air molecules when upon collision. The separation of the electrons from these air molecules creates two more ions: one negative (the electron) and one positive (the N2+ or O2+)<br /> ===Propagation of the Electric Field===<br /> Because electric fields are strongest near each of the two opposite charges, the chain reaction of ionization starts there. The new ions created through collisions with the ions accelerated by the electric field also accelerate due to the electric field. These new ions can then cause more air particles to ionize by striking them at high speeds. <br /> The negatively charged ions move towards the positively charged object that started the spark, and the positively charged ions move towards the negatively charged object. As this happens, the charge distribution in the air between the two charged objects changes. Before the spark began, the electric field emanated from the two charged objects. As ions begin to form, the electric field also emanates in part from the ionized air. This causes the electric field between the two charged object to become more uniform, much like what occurs in a wire when a circuit is closed.<br /> Eventually, the chain reactions coming from each charged object meet in the middle, and the &quot;circuit&quot; is complete.<br /> ===Neutralization of Charges===<br /> The molecules of the air are now sufficiently ionized to carry a current. The electrons in the gap move relatively rapidly toward the positively charged object, while the positive ions move very slowly towards the negatively charged object, due to the differences in their masses. As the ions hit the charged surfaces to which they are attracted, they combine with oppositely charged particles on that object's surface. When this happens, the charge on each object diminishes due to the cancellation of fields. Soon, there is no longer enough charge on the objects to accelerate the ions enough to maintain an ionized air gap.<br /> As the charged particles move through, the air, they are constantly recombining with other ions in the process of random motion, before being again knocked apart by an accelerated charge. Sparks produce light because when molecules recombine, they move to a lower energy state, and emit the difference in energy as a photon. These continual reactions produce a lot of heat, which cases the air gap to rapidly expand and make the sound we hear when a spark occurs.<br /> ==A Mathematical Model==<br /> <br /> Let's run through a mathematical model of the situation to make sure that the numbers match up with our observations.<br /> How much of an electric field is required to accelerate the electrons enough to cause a chain reaction? At ground level, the average distance an air particle can travel before it makes contact with another is &lt;math&gt;1E-6m&lt;/math&gt;[http://physics.bu.edu/~redner/211-sp06/class-macro-micro/kinetic_meanfreepath.html]. This is known as the mean free path. Over this small of a distance, we can assume that the electric field will be roughly uniform. <br /> If we know that the average ionization energy for an air molecule is roughly &lt;math&gt;2E-18J&lt;/math&gt;[http://www.webelements.com/], then we can calculate what electric field magnitude will be necessary to cause a spark.<br /> <br /> &lt;math&gt;E |\!-\!e|&lt;/math&gt; constitutes the force applied to a free electron by the electric field, so<br /> <br /> &lt;math&gt;E e d&lt;/math&gt; must be the kinetic energy imparted to the electron over the mean free path, where &lt;math&gt;d&lt;/math&gt; is the mean free path.<br /> <br /> &lt;math&gt;E e d = K&lt;/math&gt;<br /> <br /> &lt;math&gt;E = {\frac{K}{ed}}&lt;/math&gt;<br /> <br /> &lt;math&gt;E = {\frac{(2E-18J)}{(1.6E-19C)(1E-6m)}}&lt;/math&gt;<br /> <br /> &lt;math&gt;E = 1.2E7{\frac{N}{C}}&lt;/math&gt;<br /> <br /> The experimentally observed value for &lt;math&gt;E&lt;/math&gt; is &lt;math&gt;3E6&lt;/math&gt;<br /> <br /> Should our answer be regarded as accurate? Knowing that air molecules, on average, already carry some kinetic energy before being stricken by accelerated ions, and that some of the ions will travel a much longer distance than the mean free path before hitting an air molecule, it is not surprising that our simplified calculation overestimates the amount of field required to cause a spark.<br /> <br /> ==History==<br /> Although it is well known that the greeks were aware of the phenomenon of electrical sparks, Leibniz formalized his observations of electric sparks in 1671. In 1716, Newton observes &quot;miniature sheet lightning&quot;. Franklin makes similar observations. In 1729, Gray discovers the conductivity of metals. In 1745, Haller reports that lightning tends to travel along metal objects, just like sparks. In 1749 Ben Franklin formalizes his idea for the experiment that would contribute his description of electricity, and in 1750 he suggests the idea for the lightning rod.<br /> ==Connectedness==<br /> [https://en.wikipedia.org/wiki/Lightning]Lightning is essentially a large spark between the earth's surface and the surface of a cloud.<br /> [https://en.wikipedia.org/wiki/Plasma_(physics)}Ionized air is also known as plasma, which most notably occurs in the sun.<br /> ==References==<br /> [http://www.nuffieldfoundation.org/practical-physics/sparks-air] Nuffield Foundation: ''Sparks In Air''<br /> <br /> [http://www.physics.csbsju.edu/370/jcalvert/dischg.htm.html] Saint Benedict Saint John's University: Electrical Discharges<br /> <br /> [http://link.springer.com/article/10.1007%2FBF02017730] N. Kyzhanovsky: Mapping the History of Electricity<br /> <br /> ==Category==<br /> [[Fields]]</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=15262 2015-12-05T20:29:41Z

<p>Brainmurphy: </p> <hr /> <div>The phenomenon of an electric field causing air to ionize such that the air emits light and sound is known as a spark. Sparks occur between two opposing charges, where the electric field between them is strong enough to cause the air molecules to split from their normally stable state, into positive and negative ions that can conduct current. <br /> <br /> ==The Physical Model==<br /> At a high level of abstraction, the occurrence of a spark is marked by three phases: the ionization of air particles, the propagation of the electric field in the air gap, and the neutralization of charges due to cancellation. These are no finite boundaries between these phases, although there is a general order to them, despite how quickly a spark occurs. <br /> ===Ionization of Air===<br /> In air, there is always some chance occurrence of ionized particles. However, air molecules (most notably Nitrogen and Oxygen) are very stable, so these ions do not make up a significant portion of all air molecules in our atmosphere. These stable molecules require a relatively large amount of energy to separate them from their electrons. Typically, collisions between air particles do not impart enough energy to ionize them -- separate them from some of their electrons.<br /> <br /> However, in the presence of a strong electric field, chance ions in the accelerate to very high speeds, gaining relatively large amounts of kinetic energy. In a strong enough electric field, these ions gain enough Kinetic energy to break apart air molecules when upon collision. The separation of the electrons from these air molecules creates two more ions: one negative (the electron) and one positive (the N2+ or O2+)<br /> ===Propagation of the Electric Field===<br /> Because electric fields are strongest near each of the two opposite charges, the chain reaction of ionization starts there. The new ions created through collisions with the ions accelerated by the electric field also accelerate due to the electric field. These new ions can then cause more air particles to ionize by striking them at high speeds. <br /> The negatively charged ions move towards the positively charged object that started the spark, and the positively charged ions move towards the negatively charged object. As this happens, the charge distribution in the air between the two charged objects changes. Before the spark began, the electric field emanated from the two charged objects. As ions begin to form, the electric field also emanates in part from the ionized air. This causes the electric field between the two charged object to become more uniform, much like what occurs in a wire when a circuit is closed.<br /> Eventually, the chain reactions coming from each charged object meet in the middle, and the &quot;circuit&quot; is complete.<br /> ===Neutralization of Charges===<br /> The molecules of the air are now sufficiently ionized to carry a current. The electrons in the gap move relatively rapidly toward the positively charged object, while the positive ions move very slowly towards the negatively charged object, due to the differences in their masses. As the ions hit the charged surfaces to which they are attracted, they combine with oppositely charged particles on that object's surface. When this happens, the charge on each object diminishes due to the cancellation of fields. Soon, there is no longer enough charge on the objects to accelerate the ions enough to maintain an ionized air gap.<br /> As the charged particles move through, the air, they are constantly recombining with other ions in the process of random motion, before being again knocked apart by an accelerated charge. Sparks produce light because when molecules recombine, they move to a lower energy state, and emit the difference in energy as a photon. These continual reactions produce a lot of heat, which cases the air gap to rapidly expand and make the sound we hear when a spark occurs.<br /> ==A Mathematical Model==<br /> <br /> Let's run through a mathematical model of the situation to make sure that the numbers match up with our observations.<br /> How much of an electric field is required to accelerate the electrons enough to cause a chain reaction? At ground level, the average distance an air particle can travel before it makes contact with another is &lt;math&gt;1E-6m&lt;/math&gt;[http://physics.bu.edu/~redner/211-sp06/class-macro-micro/kinetic_meanfreepath.html]. This is known as the mean free path. Over this small of a distance, we can assume that the electric field will be roughly uniform. <br /> If we know that the average ionization energy for an air molecule is roughly &lt;math&gt;2E-18J&lt;/math&gt;[http://www.webelements.com/], then we can calculate what electric field magnitude will be necessary to cause a spark.<br /> <br /> &lt;math&gt;E |\!-\!e|&lt;/math&gt; constitutes the force applied a free electron by the electric field, so<br /> <br /> &lt;math&gt;E e d&lt;/math&gt; must be the kinetic energy imparted to the electron over the mean free path, where &lt;math&gt;d&lt;/math&gt; is the mean free path.<br /> <br /> &lt;math&gt;E e d = K&lt;/math&gt;<br /> <br /> &lt;math&gt;E = {\frac{K}{ed}}&lt;/math&gt;<br /> <br /> &lt;math&gt;E = {\frac{(2E-18J)}{(1.6E-19C)(1E-6m)}}&lt;/math&gt;<br /> <br /> &lt;math&gt;E = 1.2E7{\frac{N}{C}}&lt;/math&gt;<br /> <br /> The experimentally observed value for &lt;math&gt;E&lt;/math&gt; is &lt;math&gt;3E6&lt;/math&gt;<br /> <br /> Should our answer be regarded as accurate? Knowing that air molecules, on average, already carry some kinetic energy before being stricken by accelerated ions, and that some of the ions will travel a much longer distance than the mean free path before hitting an air molecule, it is not surprising that our simplified calculation overestimates the amount of field required to cause a spark.<br /> <br /> ==History==<br /> Although it is well known that the greeks were aware of the phenomenon of electrical sparks, Leibniz formalized his observations of electric sparks in 1671. In 1716, Newton observes &quot;miniature sheet lightning&quot;. Franklin makes similar observations. In 1729, Gray discovers the conductivity of metals. In 1745, Haller reports that lightning tends to travel along metal objects, just like sparks. In 1749 Ben Franklin formalizes his idea for the experiment that would contribute his description of electricity, and in 1750 he suggests the idea for the lightning rod.<br /> ==Connectedness==<br /> [https://en.wikipedia.org/wiki/Lightning]Lightning is essentially a large spark between the earth's surface and the surface of a cloud.<br /> [https://en.wikipedia.org/wiki/Plasma_(physics)}Ionized air is also known as plasma, which most notably occurs in the sun.<br /> ==References==<br /> [http://www.nuffieldfoundation.org/practical-physics/sparks-air] Nuffield Foundation: ''Sparks In Air''<br /> <br /> [http://www.physics.csbsju.edu/370/jcalvert/dischg.htm.html] Saint Benedict Saint John's University: Electrical Discharges<br /> <br /> [http://link.springer.com/article/10.1007%2FBF02017730] N. Kyzhanovsky: Mapping the History of Electricity<br /> <br /> ==Category==<br /> [[Fields]]</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=15252 2015-12-05T20:28:04Z

<p>Brainmurphy: </p> <hr /> <div>The phenomenon of an electric field causing air to ionize such that the air emits light and sound is known as a spark. Sparks occur between two opposing charges, where the electric field between them is strong enough to cause the air molecules to split from their normally stable state, into positive and negative ions that can conduct current. <br /> <br /> ==The Physical Model==<br /> At a high level of abstraction, the occurrence of a spark is marked by three phases: the ionization of air particles, the propagation of the electric field in the air gap, and the neutralization of charges due to cancellation. These are no finite boundaries between these phases, although there is a general order to them, despite how quickly a spark occurs. <br /> ===Ionization of Air===<br /> In air, there is always some chance occurrence of ionized particles. However, air molecules (most notably Nitrogen and Oxygen) are very stable, so these ions do not make up a significant portion of all air molecules in our atmosphere. These stable molecules require a relatively large amount of energy to separate them from their electrons. Typically, collisions between air particles do not impart enough energy to ionize them -- separate them from some of their electrons.<br /> <br /> However, in the presence of a strong electric field, chance ions in the accelerate to very high speeds, gaining relatively large amounts of kinetic energy. In a strong enough electric field, these ions gain enough Kinetic energy to break apart air molecules when upon collision. The separation of the electrons from these air molecules creates two more ions: one negative (the electron) and one positive (the N2+ or O2+)<br /> ===Propagation of the Electric Field===<br /> Because electric fields are strongest near each of the two opposite charges, the chain reaction of ionization starts there. The new ions created through collisions with the ions accelerated by the electric field also accelerate due to the electric field. These new ions can then cause more air particles to ionize by striking them at high speeds. <br /> The negatively charged ions move towards the positively charged object that started the spark, and the positively charged ions move towards the negatively charged object. As this happens, the charge distribution in the air between the two charged objects changes. Before the spark began, the electric field emanated from the two charged objects. As ions begin to form, the electric field also emanates in part from the ionized air. This causes the electric field between the two charged object to become more uniform, much like what occurs in a wire when a circuit is closed.<br /> Eventually, the chain reactions coming from each charged object meet in the middle, and the &quot;circuit&quot; is complete.<br /> ===Neutralization of Charges===<br /> The molecules of the air are now sufficiently ionized to carry a current. The electrons in the gap move relatively rapidly toward the positively charged object, while the positive ions move very slowly towards the negatively charged object, due to the differences in their masses. As the ions hit the charged surfaces to which they are attracted, they combine with oppositely charged particles on that object's surface. When this happens, the charge on each object diminishes due to the cancellation of fields. Soon, there is no longer enough charge on the objects to accelerate the ions enough to maintain an ionized air gap.<br /> As the charged particles move through, the air, they are constantly recombining with other ions in the process of random motion, before being again knocked apart by an accelerated charge. Sparks produce light because when molecules recombine, they move to a lower energy state, and emit the difference in energy as a photon. These continual reactions produce a lot of heat, which cases the air gap to rapidly expand and make the sound we hear when a spark occurs.<br /> ==A Mathematical Model==<br /> <br /> Let's run through a mathematical model of the situation to make sure that the numbers match up with our observations.<br /> How much of an electric field is required to accelerate the electrons enough to cause a chain reaction? At ground level, the average distance an air particle can travel before it makes contact with another is &lt;math&gt;1E-6m&lt;/math&gt;[http://physics.bu.edu/~redner/211-sp06/class-macro-micro/kinetic_meanfreepath.html]. This is known as the mean free path. Over this small of a distance, we can assume that the electric field will be roughly uniform. <br /> If we know that the average ionization energy for an air molecule is roughly &lt;math&gt;2E-18J&lt;/math&gt;[http://www.webelements.com/], then we can calculate what electric field magnitude will be necessary to cause a spark.<br /> <br /> &lt;math&gt;(E) |\!-\!e|&lt;/math&gt; constitutes the force applied to the ion by the electric field, so<br /> <br /> &lt;math&gt;E e d&lt;/math&gt; must be the kinetic energy imparted to the ion over the mean free path, where &lt;math&gt;d&lt;/math&gt; is the mean free path.<br /> <br /> &lt;math&gt;E e d = K&lt;/math&gt;<br /> <br /> &lt;math&gt;E = {\frac{K}{ed}}&lt;/math&gt;<br /> <br /> &lt;math&gt;E = {\frac{(2E-18J)}{(1.6E-19C)(1E-6m)}}&lt;/math&gt;<br /> <br /> &lt;math&gt;E = 1.2E7{\frac{N}{C}}&lt;/math&gt;<br /> <br /> The experimentally observed value for &lt;math&gt;E&lt;/math&gt; is &lt;math&gt;3E6&lt;/math&gt;<br /> <br /> Should our answer be regarded as accurate? Knowing that air molecules, on average, already carry some kinetic energy before being stricken by accelerated ions, and that some of the ions will travel a much longer distance than the mean free path before hitting an air molecule, it is not surprising that our simplified calculation overestimates the amount of field required to cause a spark.<br /> <br /> ==History==<br /> Although it is well known that the greeks were aware of the phenomenon of electrical sparks, Leibniz formalized his observations of electric sparks in 1671. In 1716, Newton observes &quot;miniature sheet lightning&quot;. Franklin makes similar observations. In 1729, Gray discovers the conductivity of metals. In 1745, Haller reports that lightning tends to travel along metal objects, just like sparks. In 1749 Ben Franklin formalizes his idea for the experiment that would contribute his description of electricity, and in 1750 he suggests the idea for the lightning rod.<br /> ==Connectedness==<br /> [https://en.wikipedia.org/wiki/Lightning]Lightning is essentially a large spark between the earth's surface and the surface of a cloud.<br /> [https://en.wikipedia.org/wiki/Plasma_(physics)}Ionized air is also known as plasma, which most notably occurs in the sun.<br /> ==References==<br /> [http://www.nuffieldfoundation.org/practical-physics/sparks-air] Nuffield Foundation: ''Sparks In Air''<br /> <br /> [http://www.physics.csbsju.edu/370/jcalvert/dischg.htm.html] Saint Benedict Saint John's University: Electrical Discharges<br /> <br /> [http://link.springer.com/article/10.1007%2FBF02017730] N. Kyzhanovsky: Mapping the History of Electricity<br /> <br /> ==Category==<br /> [[Fields]]</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=15250 2015-12-05T20:27:43Z

<p>Brainmurphy: </p> <hr /> <div>The phenomenon of an electric field causing air to ionize such that the air emits light and sound is known as a spark. Sparks occur between two opposing charges, where the electric field between them is strong enough to cause the air molecules to split from their normally stable state, into positive and negative ions that can conduct current. <br /> <br /> ==The Physical Model==<br /> At a high level of abstraction, the occurrence of a spark is marked by three phases: the ionization of air particles, the propagation of the electric field in the air gap, and the neutralization of charges due to cancellation. These are no finite boundaries between these phases, although there is a general order to them, despite how quickly a spark occurs. <br /> ===Ionization of Air===<br /> In air, there is always some chance occurrence of ionized particles. However, air molecules (most notably Nitrogen and Oxygen) are very stable, so these ions do not make up a significant portion of all air molecules in our atmosphere. These stable molecules require a relatively large amount of energy to separate them from their electrons. Typically, collisions between air particles do not impart enough energy to ionize them -- separate them from some of their electrons.<br /> <br /> However, in the presence of a strong electric field, chance ions in the accelerate to very high speeds, gaining relatively large amounts of kinetic energy. In a strong enough electric field, these ions gain enough Kinetic energy to break apart air molecules when upon collision. The separation of the electrons from these air molecules creates two more ions: one negative (the electron) and one positive (the N2+ or O2+)<br /> ===Propagation of the Electric Field===<br /> Because electric fields are strongest near each of the two opposite charges, the chain reaction of ionization starts there. The new ions created through collisions with the ions accelerated by the electric field also accelerate due to the electric field. These new ions can then cause more air particles to ionize by striking them at high speeds. <br /> The negatively charged ions move towards the positively charged object that started the spark, and the positively charged ions move towards the negatively charged object. As this happens, the charge distribution in the air between the two charged objects changes. Before the spark began, the electric field emanated from the two charged objects. As ions begin to form, the electric field also emanates in part from the ionized air. This causes the electric field between the two charged object to become more uniform, much like what occurs in a wire when a circuit is closed.<br /> Eventually, the chain reactions coming from each charged object meet in the middle, and the &quot;circuit&quot; is complete.<br /> ===Neutralization of Charges===<br /> The molecules of the air are now sufficiently ionized to carry a current. The electrons in the gap move relatively rapidly toward the positively charged object, while the positive ions move very slowly towards the negatively charged object, due to the differences in their masses. As the ions hit the charged surfaces to which they are attracted, they combine with oppositely charged particles on that object's surface. When this happens, the charge on each object diminishes due to the cancellation of fields. Soon, there is no longer enough charge on the objects to accelerate the ions enough to maintain an ionized air gap.<br /> As the charged particles move through, the air, they are constantly recombining with other ions in the process of random motion, before being again knocked apart by an accelerated charge. Sparks produce light because when molecules recombine, they move to a lower energy state, and emit the difference in energy as a photon. These continual reactions produce a lot of heat, which cases the air gap to rapidly expand and make the sound we hear when a spark occurs.<br /> ==A Mathematical Model==<br /> <br /> Let's run through a mathematical model of the situation to make sure that the numbers match up with our observations.<br /> How much of an electric field is required to accelerate the electrons enough to cause a chain reaction? At ground level, the average distance an air particle can travel before it makes contact with another is &lt;math&gt;1E-6m&lt;/math&gt;[http://physics.bu.edu/~redner/211-sp06/class-macro-micro/kinetic_meanfreepath.html]. This is known as the mean free path. Over this small of a distance, we can assume that the electric field will be roughly uniform. <br /> If we know that the average ionization energy for an air molecule is roughly &lt;math&gt;2E-18J&lt;/math&gt;[http://www.webelements.com/], then we can calculate what electric field magnitude will be necessary to cause a spark.<br /> <br /> &lt;math&gt;(E) |\!-\!e|&lt;/math&gt; constitutes the force applied to the ion by the electric field, so<br /> <br /> &lt;math&gt;E e d&lt;/math&gt; must be the kinetic energy imparted to the ion over the mean free path, where &lt;math&gt;d&lt;math&gt; is the mean free path.<br /> <br /> &lt;math&gt;E e d = K&lt;/math&gt;<br /> <br /> &lt;math&gt;E = {\frac{K}{ed}}&lt;/math&gt;<br /> <br /> &lt;math&gt;E = {\frac{(2E-18J)}{(1.6E-19C)(1E-6m)}}&lt;/math&gt;<br /> <br /> &lt;math&gt;E = 1.2E7{\frac{N}{C}}&lt;/math&gt;<br /> <br /> The experimentally observed value for &lt;math&gt;E&lt;/math&gt; is &lt;math&gt;3E6&lt;/math&gt;<br /> <br /> Should our answer be regarded as accurate? Knowing that air molecules, on average, already carry some kinetic energy before being stricken by accelerated ions, and that some of the ions will travel a much longer distance than the mean free path before hitting an air molecule, it is not surprising that our simplified calculation overestimates the amount of field required to cause a spark.<br /> <br /> ==History==<br /> Although it is well known that the greeks were aware of the phenomenon of electrical sparks, Leibniz formalized his observations of electric sparks in 1671. In 1716, Newton observes &quot;miniature sheet lightning&quot;. Franklin makes similar observations. In 1729, Gray discovers the conductivity of metals. In 1745, Haller reports that lightning tends to travel along metal objects, just like sparks. In 1749 Ben Franklin formalizes his idea for the experiment that would contribute his description of electricity, and in 1750 he suggests the idea for the lightning rod.<br /> ==Connectedness==<br /> [https://en.wikipedia.org/wiki/Lightning]Lightning is essentially a large spark between the earth's surface and the surface of a cloud.<br /> [https://en.wikipedia.org/wiki/Plasma_(physics)}Ionized air is also known as plasma, which most notably occurs in the sun.<br /> ==References==<br /> [http://www.nuffieldfoundation.org/practical-physics/sparks-air] Nuffield Foundation: ''Sparks In Air''<br /> <br /> [http://www.physics.csbsju.edu/370/jcalvert/dischg.htm.html] Saint Benedict Saint John's University: Electrical Discharges<br /> <br /> [http://link.springer.com/article/10.1007%2FBF02017730] N. Kyzhanovsky: Mapping the History of Electricity<br /> <br /> ==Category==<br /> [[Fields]]</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=15194 2015-12-05T20:22:08Z

<p>Brainmurphy: </p> <hr /> <div>The phenomenon of an electric field causing air to ionize such that the air emits light and sound is known as a spark. Sparks occur between two opposing charges, where the electric field between them is strong enough to cause the air molecules to split from their normally stable state, into positive and negative ions that can conduct current. <br /> <br /> ==The Physical Model==<br /> At a high level of abstraction, the occurrence of a spark is marked by three phases: the ionization of air particles, the propagation of the electric field in the air gap, and the neutralization of charges due to cancellation. These are no finite boundaries between these phases, although there is a general order to them, despite how quickly a spark occurs. <br /> ===Ionization of Air===<br /> In air, there is always some chance occurrence of ionized particles. However, air molecules (most notably Nitrogen and Oxygen) are very stable, so these ions do not make up a significant portion of all air molecules in our atmosphere. These stable molecules require a relatively large amount of energy to separate them from their electrons. Typically, collisions between air particles do not impart enough energy to ionize them -- separate them from some of their electrons.<br /> <br /> However, in the presence of a strong electric field, chance ions in the accelerate to very high speeds, gaining relatively large amounts of kinetic energy. In a strong enough electric field, these ions gain enough Kinetic energy to break apart air molecules when upon collision. The separation of the electrons from these air molecules creates two more ions: one negative (the electron) and one positive (the N2+ or O2+)<br /> ===Propagation of the Electric Field===<br /> Because electric fields are strongest near each of the two opposite charges, the chain reaction of ionization starts there. The new ions created through collisions with the ions accelerated by the electric field also accelerate due to the electric field. These new ions can then cause more air particles to ionize by striking them at high speeds. <br /> The negatively charged ions move towards the positively charged object that started the spark, and the positively charged ions move towards the negatively charged object. As this happens, the charge distribution in the air between the two charged objects changes. Before the spark began, the electric field emanated from the two charged objects. As ions begin to form, the electric field also emanates in part from the ionized air. This causes the electric field between the two charged object to become more uniform, much like what occurs in a wire when a circuit is closed.<br /> Eventually, the chain reactions coming from each charged object meet in the middle, and the &quot;circuit&quot; is complete.<br /> ===Neutralization of Charges===<br /> The molecules of the air are now sufficiently ionized to carry a current. The electrons in the gap move relatively rapidly toward the positively charged object, while the positive ions move very slowly towards the negatively charged object, due to the differences in their masses. As the ions hit the charged surfaces to which they are attracted, they combine with oppositely charged particles on that object's surface. When this happens, the charge on each object diminishes due to the cancellation of fields. Soon, there is no longer enough charge on the objects to accelerate the ions enough to maintain an ionized air gap.<br /> As the charged particles move through, the air, they are constantly recombining with other ions in the process of random motion, before being again knocked apart by an accelerated charge. Sparks produce light because when molecules recombine, they move to a lower energy state, and emit the difference in energy as a photon. These continual reactions produce a lot of heat, which cases the air gap to rapidly expand and make the sound we hear when a spark occurs.<br /> ==A Mathematical Model==<br /> <br /> Let's run through a mathematical model of the situation to make sure that the numbers match up with our observations.<br /> How much of an electric field is required to accelerate the electrons enough to cause a chain reaction? At ground level, the average distance an air particle can travel before it makes contact with another is &lt;math&gt;1E-6m&lt;/math&gt;[http://physics.bu.edu/~redner/211-sp06/class-macro-micro/kinetic_meanfreepath.html]. This is known as the mean free path. Over this small of a distance, we can assume that the electric field will be roughly uniform. <br /> If we know that the average ionization energy for an air molecule is roughly &lt;math&gt;2E-18J&lt;/math&gt;[http://www.webelements.com/], then we can calculate what electric field magnitude will be necessary to cause a spark.<br /> <br /> &lt;math&gt;E |\!-\!e| d = K&lt;/math&gt;<br /> <br /> where K is the kinetic energy required to ionize an air molecule, and d is the mean free path.<br /> <br /> &lt;math&gt;E = {\frac{K}{ed}}&lt;/math&gt;<br /> <br /> &lt;math&gt;E = {\frac{(2E-18J)}{(1.6E-19C)(1E-6m)}}&lt;/math&gt;<br /> <br /> &lt;math&gt;E = 1.2E7{\frac{N}{C}}&lt;/math&gt;<br /> <br /> The experimentally observed value for &lt;math&gt;E&lt;/math&gt; is &lt;math&gt;3E6&lt;/math&gt;<br /> <br /> Should our answer be regarded as accurate? Knowing that air molecules, on average, already carry some kinetic energy before being stricken by accelerated ions, and that some of the ions will travel a much longer distance than the mean free path before hitting an air molecule, it is not surprising that our simplified calculation overestimates the amount of field required to cause a spark.<br /> <br /> ==History==<br /> Although it is well known that the greeks were aware of the phenomenon of electrical sparks, Leibniz formalized his observations of electric sparks in 1671. In 1716, Newton observes &quot;miniature sheet lightning&quot;. Franklin makes similar observations. In 1729, Gray discovers the conductivity of metals. In 1745, Haller reports that lightning tends to travel along metal objects, just like sparks. In 1749 Ben Franklin formalizes his idea for the experiment that would contribute his description of electricity, and in 1750 he suggests the idea for the lightning rod.<br /> ==Connectedness==<br /> [https://en.wikipedia.org/wiki/Lightning]Lightning is essentially a large spark between the earth's surface and the surface of a cloud.<br /> [https://en.wikipedia.org/wiki/Plasma_(physics)}Ionized air is also known as plasma, which most notably occurs in the sun.<br /> ==References==<br /> [http://www.nuffieldfoundation.org/practical-physics/sparks-air] Nuffield Foundation: ''Sparks In Air''<br /> <br /> [http://www.physics.csbsju.edu/370/jcalvert/dischg.htm.html] Saint Benedict Saint John's University: Electrical Discharges<br /> <br /> [http://link.springer.com/article/10.1007%2FBF02017730] N. Kyzhanovsky: Mapping the History of Electricity<br /> <br /> ==Category==<br /> [[Fields]]</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=15187 2015-12-05T20:21:27Z

<p>Brainmurphy: </p> <hr /> <div>The phenomenon of an electric field causing air to ionize such that the air emits light and sound is known as a spark. Sparks occur between two opposing charges, where the electric field between them is strong enough to cause the air molecules to split from their normally stable state, into positive and negative ions that can conduct current. <br /> <br /> ==The Physical Model==<br /> At a high level of abstraction, the occurrence of a spark is marked by three phases: the ionization of air particles, the propagation of the electric field in the air gap, and the neutralization of charges due to cancellation. These are no finite boundaries between these phases, although there is a general order to them, despite how quickly a spark occurs. <br /> ===Ionization of Air===<br /> In air, there is always some chance occurrence of ionized particles. However, air molecules (most notably Nitrogen and Oxygen) are very stable, so these ions do not make up a significant portion of all air molecules in our atmosphere. These stable molecules require a relatively large amount of energy to separate them from their electrons. Typically, collisions between air particles do not impart enough energy to ionize them -- separate them from some of their electrons.<br /> <br /> However, in the presence of a strong electric field, chance ions in the accelerate to very high speeds, gaining relatively large amounts of kinetic energy. In a strong enough electric field, these ions gain enough Kinetic energy to break apart air molecules when upon collision. The separation of the electrons from these air molecules creates two more ions: one negative (the electron) and one positive (the N2+ or O2+)<br /> ===Propagation of the Electric Field===<br /> Because electric fields are strongest near each of the two opposite charges, the chain reaction of ionization starts there. The new ions created through collisions with the ions accelerated by the electric field also accelerate due to the electric field. These new ions can then cause more air particles to ionize by striking them at high speeds. <br /> The negatively charged ions move towards the positively charged object that started the spark, and the positively charged ions move towards the negatively charged object. As this happens, the charge distribution in the air between the two charged objects changes. Before the spark began, the electric field emanated from the two charged objects. As ions begin to form, the electric field also emanates in part from the ionized air. This causes the electric field between the two charged object to become more uniform, much like what occurs in a wire when a circuit is closed.<br /> Eventually, the chain reactions coming from each charged object meet in the middle, and the &quot;circuit&quot; is complete.<br /> ===Neutralization of Charges===<br /> The molecules of the air are now sufficiently ionized to carry a current. The electrons in the gap move relatively rapidly toward the positively charged object, while the positive ions move very slowly towards the negatively charged object, due to the differences in their masses. As the ions hit the charged surfaces to which they are attracted, they combine with oppositely charged particles on that object's surface. When this happens, the charge on each object diminishes due to the cancellation of fields. Soon, there is no longer enough charge on the objects to accelerate the ions enough to maintain an ionized air gap.<br /> As the charged particles move through, the air, they are constantly recombining with other ions in the process of random motion, before being again knocked apart by an accelerated charge. Sparks produce light because when molecules recombine, they move to a lower energy state, and emit the difference in energy as a photon. These continual reactions produce a lot of heat, which cases the air gap to rapidly expand and make the sound we hear when a spark occurs.<br /> ==A Mathematical Model==<br /> <br /> Let's run through a mathematical model of the situation to make sure that the numbers match up with our observations.<br /> How much of an electric field is required to accelerate the electrons enough to cause a chain reaction? At ground level, the average distance an air particle can travel before it makes contact with another is &lt;math&gt;1E-6m&lt;math&gt;[http://physics.bu.edu/~redner/211-sp06/class-macro-micro/kinetic_meanfreepath.html]. This is known as the mean free path. Over this small of a distance, we can assume that the electric field will be roughly uniform. <br /> If we know that the average ionization energy for an air molecule is roughly &lt;math&gt;2E-18J&lt;/math&gt;[http://www.webelements.com/], then we can calculate what electric field magnitude will be necessary to cause a spark.<br /> <br /> &lt;math&gt;E |\!-\!e| d = K&lt;/math&gt;<br /> <br /> where K is the kinetic energy required to ionize an air molecule, and d is the mean free path.<br /> <br /> &lt;math&gt;E = {\frac{K}{ed}}&lt;/math&gt;<br /> <br /> &lt;math&gt;E = {\frac{(2E-18J)}{(1.6E-19C)(1E-6m)}}&lt;/math&gt;<br /> <br /> &lt;math&gt;E = 1.2E7{\frac{N}{C}}&lt;/math&gt;<br /> <br /> The experimentally observed value for &lt;math&gt;E&lt;/math&gt; is &lt;math&gt;3E6&lt;/math&gt;<br /> <br /> Should our answer be regarded as accurate? Knowing that air molecules, on average, already carry some kinetic energy before being stricken by accelerated ions, and that some of the ions will travel a much longer distance than the mean free path before hitting an air molecule, it is not surprising that our simplified calculation overestimates the amount of field required to cause a spark.<br /> <br /> ==History==<br /> Although it is well known that the greeks were aware of the phenomenon of electrical sparks, Leibniz formalized his observations of electric sparks in 1671. In 1716, Newton observes &quot;miniature sheet lightning&quot;. Franklin makes similar observations. In 1729, Gray discovers the conductivity of metals. In 1745, Haller reports that lightning tends to travel along metal objects, just like sparks. In 1749 Ben Franklin formalizes his idea for the experiment that would contribute his description of electricity, and in 1750 he suggests the idea for the lightning rod.<br /> ==Connectedness==<br /> [https://en.wikipedia.org/wiki/Lightning]Lightning is essentially a large spark between the earth's surface and the surface of a cloud.<br /> [https://en.wikipedia.org/wiki/Plasma_(physics)}Ionized air is also known as plasma, which most notably occurs in the sun.<br /> ==References==<br /> [http://www.nuffieldfoundation.org/practical-physics/sparks-air] Nuffield Foundation: ''Sparks In Air''<br /> <br /> [http://www.physics.csbsju.edu/370/jcalvert/dischg.htm.html] Saint Benedict Saint John's University: Electrical Discharges<br /> <br /> [http://link.springer.com/article/10.1007%2FBF02017730] N. Kyzhanovsky: Mapping the History of Electricity<br /> <br /> ==Category==<br /> [[Fields]]</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=15180 2015-12-05T20:20:18Z

<p>Brainmurphy: </p> <hr /> <div>The phenomenon of an electric field causing air to ionize such that the air emits light and sound is known as a spark. Sparks occur between two opposing charges, where the electric field between them is strong enough to cause the air molecules to split from their normally stable state, into positive and negative ions that can conduct current. <br /> <br /> ==The Physical Model==<br /> At a high level of abstraction, the occurrence of a spark is marked by three phases: the ionization of air particles, the propagation of the electric field in the air gap, and the neutralization of charges due to cancellation. These are no finite boundaries between these phases, although there is a general order to them, despite how quickly a spark occurs. <br /> ===Ionization of Air===<br /> In air, there is always some chance occurrence of ionized particles. However, air molecules (most notably Nitrogen and Oxygen) are very stable, so these ions do not make up a significant portion of all air molecules in our atmosphere. These stable molecules require a relatively large amount of energy to separate them from their electrons. Typically, collisions between air particles do not impart enough energy to ionize them -- separate them from some of their electrons.<br /> <br /> However, in the presence of a strong electric field, chance ions in the accelerate to very high speeds, gaining relatively large amounts of kinetic energy. In a strong enough electric field, these ions gain enough Kinetic energy to break apart air molecules when upon collision. The separation of the electrons from these air molecules creates two more ions: one negative (the electron) and one positive (the N2+ or O2+)<br /> ===Propagation of the Electric Field===<br /> Because electric fields are strongest near each of the two opposite charges, the chain reaction of ionization starts there. The new ions created through collisions with the ions accelerated by the electric field also accelerate due to the electric field. These new ions can then cause more air particles to ionize by striking them at high speeds. <br /> The negatively charged ions move towards the positively charged object that started the spark, and the positively charged ions move towards the negatively charged object. As this happens, the charge distribution in the air between the two charged objects changes. Before the spark began, the electric field emanated from the two charged objects. As ions begin to form, the electric field also emanates in part from the ionized air. This causes the electric field between the two charged object to become more uniform, much like what occurs in a wire when a circuit is closed.<br /> Eventually, the chain reactions coming from each charged object meet in the middle, and the &quot;circuit&quot; is complete.<br /> ===Neutralization of Charges===<br /> The molecules of the air are now sufficiently ionized to carry a current. The electrons in the gap move relatively rapidly toward the positively charged object, while the positive ions move very slowly towards the negatively charged object, due to the differences in their masses. As the ions hit the charged surfaces to which they are attracted, they combine with oppositely charged particles on that object's surface. When this happens, the charge on each object diminishes due to the cancellation of fields. Soon, there is no longer enough charge on the objects to accelerate the ions enough to maintain an ionized air gap.<br /> As the charged particles move through, the air, they are constantly recombining with other ions in the process of random motion, before being again knocked apart by an accelerated charge. Sparks produce light because when molecules recombine, they move to a lower energy state, and emit the difference in energy as a photon. These continual reactions produce a lot of heat, which cases the air gap to rapidly expand and make the sound we hear when a spark occurs.<br /> ==A Mathematical Model==<br /> <br /> Let's run through a mathematical model of the situation to make sure that the numbers match up with our observations.<br /> How much of an electric field is required to accelerate the electrons enough to cause a chain reaction? At ground level, the average distance an air particle can travel before it makes contact with another is 1E-6m[http://physics.bu.edu/~redner/211-sp06/class-macro-micro/kinetic_meanfreepath.html]. This is known as the mean free path. Over this small of a distance, we can assume that the electric field will be roughly uniform. <br /> [http://www.webelements.com/]If we know that the average ionization energy for an air molecule is roughly &lt;math&gt;2E-18J&lt;/math&gt;, then we can calculate what electric field magnitude will be necessary to cause a spark.<br /> <br /> &lt;math&gt;E |\!-\!e| d = K&lt;/math&gt;<br /> <br /> where K is the kinetic energy required to ionize an air molecule, and d is the mean free path.<br /> <br /> &lt;math&gt;E = {\frac{K}{ed}}&lt;/math&gt;<br /> <br /> &lt;math&gt;E = {\frac{(2E-18J)}{(1.6E-19C)(1E-6m)}}&lt;/math&gt;<br /> <br /> &lt;math&gt;E = 1.2E7{\frac{N}{C}}&lt;/math&gt;<br /> <br /> The experimentally observed value for &lt;math&gt;E&lt;/math&gt; is &lt;math&gt;3E6&lt;/math&gt;<br /> <br /> Should our answer be regarded as accurate? Knowing that air molecules, on average, already carry some kinetic energy before being stricken by accelerated ions, and that some of the ions will travel a much longer distance than the mean free path before hitting an air molecule, it is not surprising that our simplified calculation overestimates the amount of field required to cause a spark.<br /> <br /> ==History==<br /> Although it is well known that the greeks were aware of the phenomenon of electrical sparks, Leibniz formalized his observations of electric sparks in 1671. In 1716, Newton observes &quot;miniature sheet lightning&quot;. Franklin makes similar observations. In 1729, Gray discovers the conductivity of metals. In 1745, Haller reports that lightning tends to travel along metal objects, just like sparks. In 1749 Ben Franklin formalizes his idea for the experiment that would contribute his description of electricity, and in 1750 he suggests the idea for the lightning rod.<br /> ==Connectedness==<br /> [https://en.wikipedia.org/wiki/Lightning]Lightning is essentially a large spark between the earth's surface and the surface of a cloud.<br /> [https://en.wikipedia.org/wiki/Plasma_(physics)}Ionized air is also known as plasma, which most notably occurs in the sun.<br /> ==References==<br /> [http://www.nuffieldfoundation.org/practical-physics/sparks-air] Nuffield Foundation: ''Sparks In Air''<br /> <br /> [http://www.physics.csbsju.edu/370/jcalvert/dischg.htm.html] Saint Benedict Saint John's University: Electrical Discharges<br /> <br /> [http://link.springer.com/article/10.1007%2FBF02017730] N. Kyzhanovsky: Mapping the History of Electricity<br /> <br /> ==Category==<br /> [[Fields]]</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=15129 2015-12-05T20:13:17Z

<p>Brainmurphy: </p> <hr /> <div>The phenomenon of an electric field causing air to ionize such that the air emits light and sound is known as a spark. Sparks occur between two opposing charges, where the electric field between them is strong enough to cause the air molecules to split from their normally stable state, into positive and negative ions that can conduct current. <br /> <br /> ==The Physical Model==<br /> At a high level of abstraction, the occurrence of a spark is marked by three phases: the ionization of air particles, the propagation of the electric field in the air gap, and the neutralization of charges due to cancellation. These are no finite boundaries between these phases, although there is a general order to them, despite how quickly a spark occurs. <br /> ===Ionization of Air===<br /> In air, there is always some chance occurrence of ionized particles. However, air molecules (most notably Nitrogen and Oxygen) are very stable, so these ions do not make up a significant portion of all air molecules in our atmosphere. These stable molecules require a relatively large amount of energy to separate them from their electrons. Typically, collisions between air particles do not impart enough energy to ionize them -- separate them from some of their electrons.<br /> <br /> However, in the presence of a strong electric field, chance ions in the accelerate to very high speeds, gaining relatively large amounts of kinetic energy. In a strong enough electric field, these ions gain enough Kinetic energy to break apart air molecules when upon collision. The separation of the electrons from these air molecules creates two more ions: one negative (the electron) and one positive (the N2+ or O2+)<br /> ===Propagation of the Electric Field===<br /> Because electric fields are strongest near each of the two opposite charges, the chain reaction of ionization starts there. The new ions created through collisions with the ions accelerated by the electric field also accelerate due to the electric field. These new ions can then cause more air particles to ionize by striking them at high speeds. <br /> The negatively charged ions move towards the positively charged object that started the spark, and the positively charged ions move towards the negatively charged object. As this happens, the charge distribution in the air between the two charged objects changes. Before the spark began, the electric field emanated from the two charged objects. As ions begin to form, the electric field also emanates in part from the ionized air. This causes the electric field between the two charged object to become more uniform, much like what occurs in a wire when a circuit is closed.<br /> Eventually, the chain reactions coming from each charged object meet in the middle, and the &quot;circuit&quot; is complete.<br /> ===Neutralization of Charges===<br /> The molecules of the air are now sufficiently ionized to carry a current. The electrons in the gap move relatively rapidly toward the positively charged object, while the positive ions move very slowly towards the negatively charged object, due to the differences in their masses. As the ions hit the charged surfaces to which they are attracted, they combine with oppositely charged particles on that object's surface. When this happens, the charge on each object diminishes due to the cancellation of fields. Soon, there is no longer enough charge on the objects to accelerate the ions enough to maintain an ionized air gap.<br /> As the charged particles move through, the air, they are constantly recombining with other ions in the process of random motion, before being again knocked apart by an accelerated charge. Sparks produce light because when molecules recombine, they move to a lower energy state, and emit the difference in energy as a photon. These continual reactions produce a lot of heat, which cases the air gap to rapidly expand and make the sound we hear when a spark occurs.<br /> ==A Mathematical Model==<br /> <br /> Let's run through a mathematical model of the situation to make sure that the numbers match up with our observations.<br /> How much of an electric field is required to accelerate the electrons enough to cause a chain reaction? At ground level, the average distance an air particle can travel before it makes contact with another is 1E-6m[http://physics.bu.edu/~redner/211-sp06/class-macro-micro/kinetic_meanfreepath.html]. This is known as the mean free path. Over this small of a distance, we can assume that the electric field will be roughly uniform. <br /> [http://www.webelements.com/]If we know that the average ionization energy for an air molecule is roughly &lt;math&gt;2E-18J&lt;/math&gt;, then we can calculate what electric field magnitude will be necessary to cause a spark.<br /> <br /> &lt;math&gt;E |-e| d = K&lt;/math&gt;<br /> <br /> where K is the kinetic energy required to ionize an air molecule, and d is the mean free path.<br /> <br /> &lt;math&gt;E = {\frac{K}{ed}}&lt;/math&gt;<br /> <br /> &lt;math&gt;E = {\frac{(2E-18J)}{(1.6E-19C)(1E-6m)}}&lt;/math&gt;<br /> <br /> &lt;math&gt;E = 1.2E7{\frac{N}{C}}&lt;/math&gt;<br /> <br /> The experimentally observed value for &lt;math&gt;E&lt;/math&gt; is &lt;math&gt;3E6&lt;/math&gt;<br /> <br /> Should our answer be regarded as accurate? Knowing that air molecules, on average, already carry some kinetic energy before being stricken by accelerated ions, and that some of the ions will travel a much longer distance than the mean free path before hitting an air molecule, it is not surprising that our simplified calculation overestimates the amount of field required to cause a spark.<br /> <br /> ==History==<br /> Although it is well known that the greeks were aware of the phenomenon of electrical sparks, Leibniz formalized his observations of electric sparks in 1671. In 1716, Newton observes &quot;miniature sheet lightning&quot;. Franklin makes similar observations. In 1729, Gray discovers the conductivity of metals. In 1745, Haller reports that lightning tends to travel along metal objects, just like sparks. In 1749 Ben Franklin formalizes his idea for the experiment that would contribute his description of electricity, and in 1750 he suggests the idea for the lightning rod.<br /> ==Connectedness==<br /> [https://en.wikipedia.org/wiki/Lightning]Lightning is essentially a large spark between the earth's surface and the surface of a cloud.<br /> [https://en.wikipedia.org/wiki/Plasma_(physics)}Ionized air is also known as plasma, which most notably occurs in the sun.<br /> ==References==<br /> [http://www.nuffieldfoundation.org/practical-physics/sparks-air] Nuffield Foundation: ''Sparks In Air''<br /> <br /> [http://www.physics.csbsju.edu/370/jcalvert/dischg.htm.html] Saint Benedict Saint John's University: Electrical Discharges<br /> <br /> [http://link.springer.com/article/10.1007%2FBF02017730] N. Kyzhanovsky: Mapping the History of Electricity<br /> <br /> ==Category==<br /> [[Fields]]</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=14666 2015-12-05T18:45:44Z

<p>Brainmurphy: </p> <hr /> <div>The phenomenon of an electric field causing air to ionize such that the air emits light and sound is known as a spark. Sparks occur between two opposing charges, where the electric field between them is strong enough to cause the air molecules to split from their normally stable state, into positive and negative ions that can conduct current. <br /> <br /> ==The Physical Model==<br /> At a high level of abstraction, the occurrence of a spark is marked by three phases: the ionization of air particles, the propagation of the electric field in the air gap, and the neutralization of charges due to cancellation. These are no finite boundaries between these phases, although there is a general order to them, despite how quickly a spark occurs. <br /> ===Ionization of Air===<br /> In air, there is always some chance occurrence of ionized particles. However, air molecules (most notably Nitrogen and Oxygen) are very stable, so these ions do not make up a significant portion of all air molecules in our atmosphere. These stable molecules require a relatively large amount of energy to separate them from their electrons. Typically, collisions between air particles do not impart enough energy to ionize them -- separate them from some of their electrons.<br /> <br /> However, in the presence of a strong electric field, chance ions in the accelerate to very high speeds, gaining relatively large amounts of kinetic energy. In a strong enough electric field, these ions gain enough Kinetic energy to break apart air molecules when upon collision. The separation of the electrons from these air molecules creates two more ions: one negative (the electron) and one positive (the N2+ or O2+)<br /> ===Propagation of the Electric Field===<br /> Because electric fields are strongest near each of the two opposite charges, the chain reaction of ionization starts there. The new ions created through collisions with the ions accelerated by the electric field also accelerate due to the electric field. These new ions can then cause more air particles to ionize by striking them at high speeds. <br /> The negatively charged ions move towards the positively charged object that started the spark, and the positively charged ions move towards the negatively charged object. As this happens, the charge distribution in the air between the two charged objects changes. Before the spark began, the electric field emanated from the two charged objects. As ions begin to form, the electric field also emanates in part from the ionized air. This causes the electric field between the two charged object to become more uniform, much like what occurs in a wire when a circuit is closed.<br /> Eventually, the chain reactions coming from each charged object meet in the middle, and the &quot;circuit&quot; is complete.<br /> ===Neutralization of Charges===<br /> The molecules of the air are now sufficiently ionized to carry a current. The electrons in the gap move relatively rapidly toward the positively charged object, while the positive ions move very slowly towards the negatively charged object, due to the differences in their masses. As the ions hit the charged surfaces to which they are attracted, they combine with oppositely charged particles on that object's surface. When this happens, the charge on each object diminishes due to the cancellation of fields. Soon, there is no longer enough charge on the objects to accelerate the ions enough to maintain an ionized air gap.<br /> As the charged particles move through, the air, they are constantly recombining with other ions in the process of random motion, before being again knocked apart by an accelerated charge. Sparks produce light because when molecules recombine, they move to a lower energy state, and emit the difference in energy as a photon. These continual reactions produce a lot of heat, which cases the air gap to rapidly expand and make the sound we hear when a spark occurs.<br /> ==A Mathematical Model==<br /> <br /> Let's run through a mathematical model of the situation to make sure that the numbers match up with our observations.<br /> How much of an electric field is required to accelerate the electrons enough to cause a chain reaction? At ground level, the average distance an air particle can travel before it makes contact with another is 1E-6m[http://physics.bu.edu/~redner/211-sp06/class-macro-micro/kinetic_meanfreepath.html]. This is known as the mean free path. Over this small of a distance, we can assume that the electric field will be roughly uniform. <br /> [http://www.webelements.com/]If we know that the average ionization energy for an air molecule is roughly &lt;math&gt;2E-18J&lt;/math&gt;, then we can calculate what electric field magnitude will be necessary to cause a spark.<br /> <br /> &lt;math&gt;E |-e| d = K&lt;/math&gt;<br /> <br /> where K is the kinetic energy required to ionize an air molecule, and d is the mean free path.<br /> <br /> &lt;math&gt;E = {\frac{K}{ed}}&lt;/math&gt;<br /> <br /> &lt;math&gt;E = {\frac{(2E-18J)}{(1.6E-19C)(1E-6m)}}&lt;/math&gt;<br /> <br /> &lt;math&gt;E = 1.2E7{/frac{N}{C}}&lt;/math&gt;<br /> <br /> The experimentally observed value for E is 3E6<br /> <br /> &lt;math&gt;{\frac{d\vec{p}}{dt}}_{system} = \vec{F}_{net}&lt;/math&gt; where '''p''' is the momentum of the system and '''F''' is the net force from the surroundings.<br /> <br /> ==History==<br /> Although it is well known that the greeks were aware of the phenomenon of electrical sparks, Leibniz formalized his observations of electric sparks in 1671. In 1716, Newton observes &quot;miniature sheet lightning&quot;. Franklin makes similar observations. In 1729, Gray discovers the conductivity of metals. In 1745, Haller reports that lightning tends to travel along metal objects, just like sparks. In 1749 Ben Franklin formalizes his idea for the experiment that would contribute his description of electricity, and in 1750 he suggests the idea for the lightning rod.<br /> ==Connectedness==<br /> [https://en.wikipedia.org/wiki/Lightning]Lightning is essentially a large spark between the earth's surface and the surface of a cloud.<br /> [https://en.wikipedia.org/wiki/Plasma_(physics)}Ionized air is also known as plasma, which most notably occurs in the sun.<br /> ==References==<br /> [http://www.nuffieldfoundation.org/practical-physics/sparks-air] Nuffield Foundation: ''Sparks In Air''<br /> <br /> [http://www.physics.csbsju.edu/370/jcalvert/dischg.htm.html] Saint Benedict Saint John's University: Electrical Discharges<br /> <br /> [http://link.springer.com/article/10.1007%2FBF02017730] N. Kyzhanovsky: Mapping the History of Electricity<br /> <br /> ==Category==<br /> [[Fields]]</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=14592 2015-12-05T18:27:30Z

<p>Brainmurphy: </p> <hr /> <div>The phenomenon of an electric field causing air to ionize such that the air emits light and sound is known as a spark. Sparks occur between two opposing charges, where the electric field between them is strong enough to cause the air molecules to split from their normally stable state, into positive and negative ions that can conduct current. <br /> <br /> ==The Physical Model==<br /> At a high level of abstraction, the occurrence of a spark is marked by three phases: the ionization of air particles, the propagation of the electric field in the air gap, and the neutralization of charges due to cancellation. These are no finite boundaries between these phases, although there is a general order to them, despite how quickly a spark occurs. <br /> ===Ionization of Air===<br /> In air, there is always some chance occurrence of ionized particles. However, air molecules (most notably Nitrogen and Oxygen) are very stable, so these ions do not make up a significant portion of all air molecules in our atmosphere. These stable molecules require a relatively large amount of energy to separate them from their electrons. Typically, collisions between air particles do not impart enough energy to ionize them -- separate them from some of their electrons.<br /> <br /> However, in the presence of a strong electric field, chance ions in the accelerate to very high speeds, gaining relatively large amounts of kinetic energy. In a strong enough electric field, these ions gain enough Kinetic energy to break apart air molecules when upon collision. The separation of the electrons from these air molecules creates two more ions: one negative (the electron) and one positive (the N2+ or O2+)<br /> ===Propagation of the Electric Field===<br /> Because electric fields are strongest near each of the two opposite charges, the chain reaction of ionization starts there. The new ions created through collisions with the ions accelerated by the electric field also accelerate due to the electric field. These new ions can then cause more air particles to ionize by striking them at high speeds. <br /> The negatively charged ions move towards the positively charged object that started the spark, and the positively charged ions move towards the negatively charged object. As this happens, the charge distribution in the air between the two charged objects changes. Before the spark began, the electric field emanated from the two charged objects. As ions begin to form, the electric field also emanates in part from the ionized air. This causes the electric field between the two charged object to become more uniform, much like what occurs in a wire when a circuit is closed.<br /> Eventually, the chain reactions coming from each charged object meet in the middle, and the &quot;circuit&quot; is complete.<br /> ===Neutralization of Charges===<br /> The molecules of the air are now sufficiently ionized to carry a current. The electrons in the gap move relatively rapidly toward the positively charged object, while the positive ions move very slowly towards the negatively charged object, due to the differences in their masses. As the ions hit the charged surfaces to which they are attracted, they combine with oppositely charged particles on that object's surface. When this happens, the charge on each object diminishes due to the cancellation of fields. Soon, there is no longer enough charge on the objects to accelerate the ions enough to maintain an ionized air gap.<br /> As the charged particles move through, the air, they are constantly recombining with other ions in the process of random motion, before being again knocked apart by an accelerated charge. Sparks produce light because when molecules recombine, they move to a lower energy state, and emit the difference in energy as a photon. These continual reactions produce a lot of heat, which cases the air gap to rapidly expand and make the sound we hear when a spark occurs.<br /> ==A Mathematical Model==<br /> <br /> Let's run through a mathematical model of the situation to make sure that the numbers match up with our observations.<br /> How much of an electric field is required to accelerate the electrons enough to cause a chain reaction? At ground level, the average distance an air particle can travel before it makes contact with another is 6.8E-8m[http://www.sciencedirect.com/science/article/pii/0021850288902194]. This is known as the mean free path. Over this small of a distance, we can assume that the electric field will be roughly uniform. <br /> [http://www.webelements.com/]If we know that the average ionization energy for an air molecule is roughly &lt;math&gt;2E-18J&lt;/math&gt;, then we can calculate what electric field magnitude will be necessary to cause a spark.<br /> <br /> &lt;math&gt;K = E |-e| d&lt;/math&gt;<br /> where K is the kinetic energy required to ionize an air molecule, and d is the mean free path.<br /> <br /> &lt;math&gt;{\frac{d\vec{p}}{dt}}_{system} = \vec{F}_{net}&lt;/math&gt; where '''p''' is the momentum of the system and '''F''' is the net force from the surroundings.<br /> <br /> ==History==<br /> Although it is well known that the greeks were aware of the phenomenon of electrical sparks, Leibniz formalized his observations of electric sparks in 1671. In 1716, Newton observes &quot;miniature sheet lightning&quot;. Franklin makes similar observations. In 1729, Gray discovers the conductivity of metals. In 1745, Haller reports that lightning tends to travel along metal objects, just like sparks. In 1749 Ben Franklin formalizes his idea for the experiment that would contribute his description of electricity, and in 1750 he suggests the idea for the lightning rod.<br /> ==Connectedness==<br /> [https://en.wikipedia.org/wiki/Lightning]Lightning is essentially a large spark between the earth's surface and the surface of a cloud.<br /> [https://en.wikipedia.org/wiki/Plasma_(physics)}Ionized air is also known as plasma, which most notably occurs in the sun.<br /> ==References==<br /> [http://www.nuffieldfoundation.org/practical-physics/sparks-air] Nuffield Foundation: ''Sparks In Air''<br /> <br /> [http://www.physics.csbsju.edu/370/jcalvert/dischg.htm.html] Saint Benedict Saint John's University: Electrical Discharges<br /> <br /> [http://link.springer.com/article/10.1007%2FBF02017730] N. Kyzhanovsky: Mapping the History of Electricity<br /> <br /> ==Category==<br /> [[Fields]]</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=13322 2015-12-05T03:54:42Z

<p>Brainmurphy: </p> <hr /> <div>The phenomenon of an electric field causing air to ionize such that the air emits light and sound is known as a spark. Sparks occur between two opposing charges, where the electric field between them is strong enough to cause the air molecules to split from their normally stable state, into positive and negative ions that can conduct current. <br /> <br /> ==The Physical Model==<br /> At a high level of abstraction, the occurrence of a spark is marked by three phases: the ionization of air particles, the propagation of the electric field in the air gap, and the neutralization of charges due to cancellation. These are no finite boundaries between these phases, although there is a general order to them, despite how quickly a spark occurs. <br /> ===Ionization of Air===<br /> In air, there is always some chance occurrence of ionized particles. However, air molecules (most notably Nitrogen and Oxygen) are very stable, so these ions do not make up a significant portion of all air molecules in our atmosphere. These stable molecules require a relatively large amount of energy to separate them from their electrons. Typically, collisions between air particles do not impart enough energy to ionize them -- separate them from some of their electrons.<br /> <br /> However, in the presence of a strong electric field, chance ions in the accelerate to very high speeds, gaining relatively large amounts of kinetic energy. In a strong enough electric field, these ions gain enough Kinetic energy to break apart air molecules when upon collision. The separation of the electrons from these air molecules creates two more ions: one negative (the electron) and one positive (the N2+ or O2+)<br /> ===Propagation of the Electric Field===<br /> Because electric fields are strongest near each of the two opposite charges, the chain reaction of ionization starts there. The new ions created through collisions with the ions accelerated by the electric field also accelerate due to the electric field. These new ions can then cause more air particles to ionize by striking them at high speeds. <br /> The negatively charged ions move towards the positively charged object that started the spark, and the positively charged ions move towards the negatively charged object. As this happens, the charge distribution in the air between the two charged objects changes. Before the spark began, the electric field emanated from the two charged objects. As ions begin to form, the electric field also emanates in part from the ionized air. This causes the electric field between the two charged object to become more uniform, much like what occurs in a wire when a circuit is closed.<br /> Eventually, the chain reactions coming from each charged object meet in the middle, and the &quot;circuit&quot; is complete.<br /> ===Neutralization of Charges===<br /> The molecules of the air are now sufficiently ionized to carry a current. The electrons in the gap move relatively rapidly toward the positively charged object, while the positive ions move very slowly towards the negatively charged object, due to the differences in their masses. As the ions hit the charged surfaces to which they are attracted, they combine with oppositely charged particles on that object's surface. When this happens, the charge on each object diminishes due to the cancellation of fields. Soon, there is no longer enough charge on the objects to accelerate the ions enough to maintain an ionized air gap.<br /> As the charged particles move through, the air, they are constantly recombining with other ions in the process of random motion, before being again knocked apart by an accelerated charge. Sparks produce light because when molecules recombine, they move to a lower energy state, and emit the difference in energy as a photon. These continual reactions produce a lot of heat, which cases the air gap to rapidly expand and make the sound we hear when a spark occurs.<br /> ==A Mathematical Model==<br /> <br /> Let's run through a mathematical model of the situation to make sure that the numbers match up with our observations.<br /> How much of an electric field is required to accelerate the electrons enough to cause a chain reaction? At ground level, the average distance an air particle can travel before it makes contact with another is 6.8E-8m[http://www.sciencedirect.com/science/article/pii/0021850288902194]. This is known as the mean free path. Over this small of a distance, we can assume that the electric field will be roughly uniform. <br /> [http://www.webelements.com/]If we know that the average ionization energy for an air molecule is roughly &lt;math&gt;2E-18J&lt;/math&gt;, then we can calculate what electric field magnitude will be necessary to cause a spark.<br /> <br /> &lt;math&gt;K = E|-e|d&lt;/math&gt;<br /> where K is the kinetic energy required to ionize an air molecule.<br /> <br /> &lt;math&gt;{\frac{d\vec{p}}{dt}}_{system} = \vec{F}_{net}&lt;/math&gt; where '''p''' is the momentum of the system and '''F''' is the net force from the surroundings.<br /> <br /> ==History==<br /> Although it is well known that the greeks were aware of the phenomenon of electrical sparks, Leibniz formalized his observations of electric sparks in 1671. In 1716, Newton observes &quot;miniature sheet lightning&quot;. Franklin makes similar observations. In 1729, Gray discovers the conductivity of metals. In 1745, Haller reports that lightning tends to travel along metal objects, just like sparks. In 1749 Ben Franklin formalizes his idea for the experiment that would contribute his description of electricity, and in 1750 he suggests the idea for the lightning rod.<br /> ==Connectedness==<br /> [https://en.wikipedia.org/wiki/Lightning]Lightning is essentially a large spark between the earth's surface and the surface of a cloud.<br /> [https://en.wikipedia.org/wiki/Plasma_(physics)}Ionized air is also known as plasma, which most notably occurs in the sun.<br /> ==References==<br /> [http://www.nuffieldfoundation.org/practical-physics/sparks-air] Nuffield Foundation: ''Sparks In Air''<br /> <br /> [http://www.physics.csbsju.edu/370/jcalvert/dischg.htm.html] Saint Benedict Saint John's University: Electrical Discharges<br /> <br /> [http://link.springer.com/article/10.1007%2FBF02017730] N. Kyzhanovsky: Mapping the History of Electricity<br /> <br /> ==Category==<br /> [[Fields]]</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=13119 2015-12-05T02:33:34Z

<p>Brainmurphy: </p> <hr /> <div>The phenomenon of an electric field causing air to ionize such that the air emits light and sound is known as a spark. Sparks occur between two opposing charges, where the electric field between them is strong enough to cause the air molecules to split from their normally stable state, into positive and negative ions that can conduct current. <br /> <br /> ==The Physical Model==<br /> At a high level of abstraction, the occurrence of a spark is marked by three phases: the ionization of air particles, the propagation of the electric field in the air gap, and the neutralization of charges due to cancellation. These are no finite boundaries between these phases, although there is a general order to them, despite how quickly a spark occurs. <br /> ===Ionization of Air===<br /> In air, there is always some chance occurrence of ionized particles. However, air molecules (most notably Nitrogen and Oxygen) are very stable, so these ions do not make up a significant portion of all air molecules in our atmosphere. These stable molecules require a relatively large amount of energy to separate them from their electrons. Typically, collisions between air particles do not impart enough energy to ionize them -- separate them from some of their electrons.<br /> <br /> However, in the presence of a strong electric field, chance ions in the accelerate to very high speeds, gaining relatively large amounts of kinetic energy. In a strong enough electric field, these ions gain enough Kinetic energy to break apart air molecules when upon collision. The separation of the electrons from these air molecules creates two more ions: one negative (the electron) and one positive (the N2+ or O2+)<br /> ===Propagation of the Electric Field===<br /> Because electric fields are strongest near each of the two opposite charges, the chain reaction of ionization starts there. The new ions created through collisions with the ions accelerated by the electric field also accelerate due to the electric field. These new ions can then cause more air particles to ionize by striking them at high speeds. <br /> The negatively charged ions move towards the positively charged object that started the spark, and the positively charged ions move towards the negatively charged object. As this happens, the charge distribution in the air between the two charged objects changes. Before the spark began, the electric field emanated from the two charged objects. As ions begin to form, the electric field also emanates in part from the ionized air. This causes the electric field between the two charged object to become more uniform, much like what occurs in a wire when a circuit is closed.<br /> Eventually, the chain reactions coming from each charged object meet in the middle, and the &quot;circuit&quot; is complete.<br /> ===Neutralization of Charges===<br /> The molecules of the air are now sufficiently ionized to carry a current. The electrons in the gap move relatively rapidly toward the positively charged object, while the positive ions move very slowly towards the negatively charged object, due to the differences in their masses. As the ions hit the charged surfaces to which they are attracted, they combine with oppositely charged particles on that object's surface. When this happens, the charge on each object diminishes due to the cancellation of fields. Soon, there is no longer enough charge on the objects to accelerate the ions enough to maintain an ionized air gap.<br /> As the charged particles move through, the air, they are constantly recombining with other ions in the process of random motion, before being again knocked apart by an accelerated charge. Sparks produce light because when molecules recombine, they move to a lower energy state, and emit the difference in energy as a photon. These continual reactions produce a lot of heat, which cases the air gap to rapidly expand and make the sound we hear when a spark occurs.<br /> ==A Mathematical Model==<br /> <br /> Let's run through a mathematical model of the situation to make sure that the numbers match up with our observations.<br /> How much of an electric field is required to accelerate the electrons enough to cause a chain reaction? At ground level, the average distance an air particle can travel before it makes contact with another is 6.8E-8m[http://www.sciencedirect.com/science/article/pii/0021850288902194]. This is known as the mean free path. Over this small of a distance, we can assume that the electric field will be roughly uniform. <br /> [http://www.webelements.com/]If we know that the average ionization energy for an air molecule is roughly 2E-18J, then we can calculate what electric field magnitude will be necessary to cause a spark.<br /> &lt;math&gt;K = E|-e|d&lt;/math&gt;<br /> &lt;math&gt;{\frac{d\vec{p}}{dt}}_{system} = \vec{F}_{net}&lt;/math&gt; where '''p''' is the momentum of the system and '''F''' is the net force from the surroundings.<br /> <br /> ==History==<br /> Although it is well known that the greeks were aware of the phenomenon of electrical sparks, Leibniz formalized his observations of electric sparks in 1671. In 1716, Newton observes &quot;miniature sheet lightning&quot;. Franklin makes similar observations. In 1729, Gray discovers the conductivity of metals. In 1745, Haller reports that lightning tends to travel along metal objects, just like sparks. In 1749 Ben Franklin formalizes his idea for the experiment that would contribute his description of electricity, and in 1750 he suggests the idea for the lightning rod.<br /> ==Connectedness==<br /> [https://en.wikipedia.org/wiki/Lightning]Lightning is essentially a large spark between the earth's surface and the surface of a cloud.<br /> [https://en.wikipedia.org/wiki/Plasma_(physics)}Ionized air is also known as plasma, which most notably occurs in the sun.<br /> ==References==<br /> [http://www.nuffieldfoundation.org/practical-physics/sparks-air] Nuffield Foundation: ''Sparks In Air''<br /> <br /> [http://www.physics.csbsju.edu/370/jcalvert/dischg.htm.html] Saint Benedict Saint John's University: Electrical Discharges<br /> <br /> [http://link.springer.com/article/10.1007%2FBF02017730] N. Kyzhanovsky: Mapping the History of Electricity<br /> <br /> ==Category==<br /> [[Fields]]</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=13112 2015-12-05T02:29:40Z

<p>Brainmurphy: </p> <hr /> <div>The phenomenon of an electric field causing air to ionize such that the air emits light and sound is known as a spark. Sparks occur between two opposing charges, where the electric field between them is strong enough to cause the air molecules to split from their normally stable state, into positive and negative ions that can conduct current. <br /> <br /> ==The Physical Model==<br /> At a high level of abstraction, the occurrence of a spark is marked by three phases: the ionization of air particles, the propagation of the electric field in the air gap, and the neutralization of charges due to cancellation. These are no finite boundaries between these phases, although there is a general order to them, despite how quickly a spark occurs. <br /> ===Ionization of Air===<br /> In air, there is always some chance occurrence of ionized particles. However, air molecules (most notably Nitrogen and Oxygen) are very stable, so these ions do not make up a significant portion of all air molecules in our atmosphere. These stable molecules require a relatively large amount of energy to separate them from their electrons. Typically, collisions between air particles do not impart enough energy to ionize them -- separate them from some of their electrons.<br /> <br /> However, in the presence of a strong electric field, chance ions in the accelerate to very high speeds, gaining relatively large amounts of kinetic energy. In a strong enough electric field, these ions gain enough Kinetic energy to break apart air molecules when upon collision. The separation of the electrons from these air molecules creates two more ions: one negative (the electron) and one positive (the N2+ or O2+)<br /> ===Propagation of the Electric Field===<br /> Because electric fields are strongest near each of the two opposite charges, the chain reaction of ionization starts there. The new ions created through collisions with the ions accelerated by the electric field also accelerate due to the electric field. These new ions can then cause more air particles to ionize by striking them at high speeds. <br /> The negatively charged ions move towards the positively charged object that started the spark, and the positively charged ions move towards the negatively charged object. As this happens, the charge distribution in the air between the two charged objects changes. Before the spark began, the electric field emanated from the two charged objects. As ions begin to form, the electric field also emanates in part from the ionized air. This causes the electric field between the two charged object to become more uniform, much like what occurs in a wire when a circuit is closed.<br /> Eventually, the chain reactions coming from each charged object meet in the middle, and the &quot;circuit&quot; is complete.<br /> ===Neutralization of Charges===<br /> The molecules of the air are now sufficiently ionized to carry a current. The electrons in the gap move relatively rapidly toward the positively charged object, while the positive ions move very slowly towards the negatively charged object, due to the differences in their masses. As the ions hit the charged surfaces to which they are attracted, they combine with oppositely charged particles on that object's surface. When this happens, the charge on each object diminishes due to the cancellation of fields. Soon, there is no longer enough charge on the objects to accelerate the ions enough to maintain an ionized air gap.<br /> As the charged particles move through, the air, they are constantly recombining with other ions in the process of random motion, before being again knocked apart by an accelerated charge. Sparks produce light because when molecules recombine, they move to a lower energy state, and emit the difference in energy as a photon. These continual reactions produce a lot of heat, which cases the air gap to rapidly expand and make the sound we hear when a spark occurs.<br /> ==A Mathematical Model==<br /> <br /> Let's run through a mathematical model of the situation to make sure that the numbers match up with our observations.<br /> How much of an electric field is required to accelerate the electrons enough to cause a chain reaction? At ground level, the average distance an air particle can travel before it makes contact with another is 6.8E-8m[http://www.sciencedirect.com/science/article/pii/0021850288902194]. This is known as the mean free path. Over this small of a distance, we can assume that the electric field will be roughly uniform. <br /> [http://www.webelements.com/]If we know that the average ionization energy for an air molecule is roughly 2E-18J, then we can calculate what electric field magnitude will be necessary to cause a spark.<br /> &lt;math&gt;{K=<br /> &lt;math&gt;{\frac{d\vec{p}}{dt}}_{system} = \vec{F}_{net}&lt;/math&gt; where '''p''' is the momentum of the system and '''F''' is the net force from the surroundings.<br /> <br /> ==History==<br /> Although it is well known that the greeks were aware of the phenomenon of electrical sparks, Leibniz formalized his observations of electric sparks in 1671. In 1716, Newton observes &quot;miniature sheet lightning&quot;. Franklin makes similar observations. In 1729, Gray discovers the conductivity of metals. In 1745, Haller reports that lightning tends to travel along metal objects, just like sparks. In 1749 Ben Franklin formalizes his idea for the experiment that would contribute his description of electricity, and in 1750 he suggests the idea for the lightning rod.<br /> ==Connectedness==<br /> [https://en.wikipedia.org/wiki/Lightning]Lightning is essentially a large spark between the earth's surface and the surface of a cloud.<br /> [https://en.wikipedia.org/wiki/Plasma_(physics)}Ionized air is also known as plasma, which most notably occurs in the sun.<br /> ==References==<br /> [http://www.nuffieldfoundation.org/practical-physics/sparks-air] Nuffield Foundation: ''Sparks In Air''<br /> <br /> [http://www.physics.csbsju.edu/370/jcalvert/dischg.htm.html] Saint Benedict Saint John's University: Electrical Discharges<br /> <br /> [http://link.springer.com/article/10.1007%2FBF02017730] N. Kyzhanovsky: Mapping the History of Electricity<br /> <br /> [[Fields]]</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=13031 2015-12-05T01:22:56Z

<p>Brainmurphy: </p> <hr /> <div>The phenomenon of an electric field causing air to ionize such that the air emits light and sound is known as a spark. Sparks occur between two opposing charges, where the electric field between them is strong enough to cause the air molecules to split from their normally stable state, into positive and negative ions that can conduct current. <br /> <br /> ==The Physical Model==<br /> At a high level of abstraction, the occurrence of a spark is marked by three phases: the ionization of air particles, the propagation of the electric field in the air gap, and the neutralization of charges due to cancellation. These are no finite boundaries between these phases, although there is a general order to them, despite how quickly a spark occurs. <br /> ===Ionization of Air===<br /> In air, there is always some chance occurrence of ionized particles. However, air molecules (most notably Nitrogen and Oxygen) are very stable, so these ions do not make up a significant portion of all air molecules in our atmosphere. These stable molecules require a relatively large amount of energy to separate them from their electrons. Typically, collisions between air particles do not impart enough energy to ionize them -- separate them from some of their electrons.<br /> <br /> However, in the presence of a strong electric field, chance ions in the accelerate to very high speeds, gaining relatively large amounts of kinetic energy. In a strong enough electric field, these ions gain enough Kinetic energy to break apart air molecules when upon collision. The separation of the electrons from these air molecules creates two more ions: one negative (the electron) and one positive (the N2+ or O2+)<br /> ===Propagation of the Electric Field===<br /> Because electric fields are strongest near each of the two opposite charges, the chain reaction of ionization starts there. The new ions created through collisions with the ions accelerated by the electric field also accelerate due to the electric field. These new ions can then cause more air particles to ionize by striking them at high speeds. <br /> The negatively charged ions move towards the positively charged object that started the spark, and the positively charged ions move towards the negatively charged object. As this happens, the charge distribution in the air between the two charged objects changes. Before the spark began, the electric field emanated from the two charged objects. As ions begin to form, the electric field also emanates in part from the ionized air. This causes the electric field between the two charged object to become more uniform, much like what occurs in a wire when a circuit is closed.<br /> Eventually, the chain reactions coming from each charged object meet in the middle, and the &quot;circuit&quot; is complete.<br /> ===Neutralization of Charges===<br /> The molecules of the air are now sufficiently ionized to carry a current. The electrons in the gap move relatively rapidly toward the positively charged object, while the positive ions move very slowly towards the negatively charged object, due to the differences in their masses. As the ions hit the charged surfaces to which they are attracted, they combine with oppositely charged particles on that object's surface. When this happens, the charge on each object diminishes due to the cancellation of fields. Soon, there is no longer enough charge on the objects to accelerate the ions enough to maintain an ionized air gap.<br /> As the charged particles move through, the air, they are constantly recombining with other ions in the process of random motion, before being again knocked apart by an accelerated charge. Sparks produce light because when molecules recombine, they move to a lower energy state, and emit the difference in energy as a photon. These continual reactions produce a lot of heat, which cases the air gap to rapidly expand and make the sound we hear when a spark occurs.<br /> ==A Mathematical Model==<br /> <br /> What are the mathematical equations that allow us to model this topic. For example &lt;math&gt;{\frac{d\vec{p}}{dt}}_{system} = \vec{F}_{net}&lt;/math&gt; where '''p''' is the momentum of the system and '''F''' is the net force from the surroundings.<br /> <br /> ==History==<br /> Although it is well known that the greeks were aware of the phenomenon of electrical sparks, Leibniz formalized his observations of electric sparks in 1671. In 1716, Newton observes &quot;miniature sheet lightning&quot;. Franklin makes similar observations. In 1729, Gray discovers the conductivity of metals. In 1745, Haller reports that lightning tends to travel along metal objects, just like sparks. In 1749 Ben Franklin formalizes his idea for the experiment that would contribute his description of electricity, and in 1750 he suggests the idea for the lightning rod.<br /> ==Connectedness==<br /> [https://en.wikipedia.org/wiki/Lightning]Lightning is essentially a large spark between the earth's surface and the surface of a cloud.<br /> [https://en.wikipedia.org/wiki/Plasma_(physics)}Ionized air is also known as plasma, which most notably occurs in the sun.<br /> ==References==<br /> [http://www.nuffieldfoundation.org/practical-physics/sparks-air] Nuffield Foundation: ''Sparks In Air''<br /> <br /> [http://www.physics.csbsju.edu/370/jcalvert/dischg.htm.html] Saint Benedict Saint John's University: Electrical Discharges<br /> <br /> [http://link.springer.com/article/10.1007%2FBF02017730] N. Kyzhanovsky: Mapping the History of Electricity<br /> <br /> [[Fields]]</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=13004 2015-12-05T01:08:40Z

<p>Brainmurphy: </p> <hr /> <div>The phenomenon of an electric field causing air to ionize such that the air emits light and sound is known as a spark. Sparks occur between two opposing charges, where the electric field between them is strong enough to cause the air molecules to split from their normally stable state, into positive and negative ions that can conduct current. <br /> <br /> ==The Physical Model==<br /> At a high level of abstraction, the occurrence of a spark is marked by three phases: the ionization of air particles, the propagation of the electric field in the air gap, and the neutralization of charges due to cancellation. These are no finite boundaries between these phases, although there is a general order to them, despite how quickly a spark occurs. <br /> ===Ionization of Air===<br /> In air, there is always some chance occurrence of ionized particles. However, air molecules (most notably Nitrogen and Oxygen) are very stable, so these ions do not make up a significant portion of all air molecules in our atmosphere. These stable molecules require a relatively large amount of energy to separate them from their electrons. Typically, collisions between air particles do not impart enough energy to ionize them -- separate them from some of their electrons.<br /> <br /> However, in the presence of a strong electric field, chance ions in the accelerate to very high speeds, gaining relatively large amounts of kinetic energy. In a strong enough electric field, these ions gain enough Kinetic energy to break apart air molecules when upon collision. The separation of the electrons from these air molecules creates two more ions: one negative (the electron) and one positive (the N2+ or O2+)<br /> ===Propagation of the Electric Field===<br /> Because electric fields are strongest near each of the two opposite charges, the chain reaction of ionization starts there. The new ions created through collisions with the ions accelerated by the electric field also accelerate due to the electric field. These new ions can then cause more air particles to ionize by striking them at high speeds. <br /> The negatively charged ions move towards the positively charged object that started the spark, and the positively charged ions move towards the negatively charged object. As this happens, the charge distribution in the air between the two charged objects changes. Before the spark began, the electric field emanated from the two charged objects. As ions begin to form, the electric field also emanates in part from the ionized air. This causes the electric field between the two charged object to become more uniform, much like what occurs in a wire when a circuit is closed.<br /> Eventually, the chain reactions coming from each charged object meet in the middle, and the &quot;circuit&quot; is complete.<br /> ===Neutralization of Charges===<br /> The molecules of the air are now sufficiently ionized to carry a current. The electrons in the gap move relatively rapidly toward the positively charged object, while the positive ions move very slowly towards the negatively charged object, due to the differences in their masses. As the ions hit the charged surfaces to which they are attracted, they combine with oppositely charged particles on that object's surface. When this happens, the charge on each object diminishes due to the cancellation of fields. Soon, there is no longer enough charge on the objects to accelerate the ions enough to maintain an ionized air gap.<br /> As the charged particles move through, the air, they are constantly recombining with other ions in the process of random motion, before being again knocked apart by an accelerated charge. Sparks produce light because when molecules recombine, they move to a lower energy state, and emit the difference in energy as a photon. These continual reactions produce a lot of heat, which cases the air gap to rapidly expand and make the sound we hear when a spark occurs.<br /> ==A Mathematical Model==<br /> <br /> What are the mathematical equations that allow us to model this topic. For example &lt;math&gt;{\frac{d\vec{p}}{dt}}_{system} = \vec{F}_{net}&lt;/math&gt; where '''p''' is the momentum of the system and '''F''' is the net force from the surroundings.<br /> <br /> ==History==<br /> Although it is well known that the greeks were aware of the phenomenon of electrical sparks, Leibniz formalized his observations of electric sparks in 1671. In 1716, Newton observes &quot;miniature sheet lightning&quot;. Franklin makes similar observations. In 1729, Gray discovers the conductivity of metals. In 1745, Haller reports that lightning tends to travel along metal objects, just like sparks. In 1749 Ben Franklin formalizes his idea for the experiment that would contribute his description of electricity, and in 1750 he suggests the idea for the lightning rod.<br /> ==Connectedness==<br /> [https://en.wikipedia.org/wiki/Lightning]Lightning is essentially a large spark between the earth's surface and the surface of a cloud<br /> ==References==<br /> [http://www.nuffieldfoundation.org/practical-physics/sparks-air] Nuffield Foundation: ''Sparks In Air''<br /> <br /> [http://www.physics.csbsju.edu/370/jcalvert/dischg.htm.html] Saint Benedict Saint John's University: Electrical Discharges<br /> <br /> [http://link.springer.com/article/10.1007%2FBF02017730] N. Kyzhanovsky: Mapping the History of Electricity<br /> <br /> <br /> ==References==<br /> <br /> This section contains the the references you used while writing this page<br /> <br /> [[Category:Which Category did you place this in?]]</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=12951 2015-12-05T00:35:14Z

<p>Brainmurphy: </p> <hr /> <div>The phenomenon of an electric field causing air to ionize such that the air emits light and sound is known as a spark. Sparks occur between two opposing charges, where the electric field between them is strong enough to cause the air molecules to split from their normally stable state, into positive and negative ions that can conduct current. <br /> <br /> ==The Physical Model==<br /> At a high level of abstraction, the occurrence of a spark is marked by three phases: the ionization of air particles, the propagation of the electric field in the air gap, and the neutralization of charges due to cancellation. These are no finite boundaries between these phases, although there is a general order to them, despite how quickly a spark occurs. <br /> ===Ionization of Air===<br /> In air, there is always some chance occurrence of ionized particles. However, air molecules (most notably Nitrogen and Oxygen) are very stable, so these ions do not make up a significant portion of all air molecules in our atmosphere. These stable molecules require a relatively large amount of energy to separate them from their electrons. Typically, collisions between air particles do not impart enough energy to ionize them -- separate them from some of their electrons.<br /> <br /> However, in the presence of a strong electric field, chance ions in the accelerate to very high speeds, gaining relatively large amounts of kinetic energy. In a strong enough electric field, these ions gain enough Kinetic energy to break apart air molecules when upon collision. The separation of the electrons from these air molecules creates two more ions: one negative (the electron) and one positive (the N2+ or O2+)<br /> ===Propagation of the Electric Field===<br /> Because electric fields are strongest near each of the two opposite charges, the chain reaction of ionization starts there. The new ions created through collisions with the ions accelerated by the electric field also accelerate due to the electric field. These new ions can then cause more air particles to ionize by striking them at high speeds. <br /> The negatively charged ions move towards the positively charged object that started the spark, and the positively charged ions move towards the negatively charged object. As this happens, the charge distribution in the air between the two charged objects changes. Before the spark began, the electric field emanated from the two charged objects. As ions begin to form, the electric field also emanates in part from the ionized air. This causes the electric field between the two charged object to become more uniform, much like what occurs in a wire when a circuit is closed.<br /> Eventually, the chain reactions coming from each charged object meet in the middle, and the &quot;circuit&quot; is complete.<br /> ===Neutralization of Charges===<br /> The molecules of the air are now sufficiently ionized to carry a current. The electrons in the gap move relatively rapidly toward the positively charged object, while the positive ions move very slowly towards the negatively charged object, due to the differences in their masses. As the ions hit the charged surfaces to which they are attracted, they combine with oppositely charged particles on that object's surface. When this happens, the charge on each object diminishes due to the cancellation of fields. Soon, there is no longer enough charge on the objects to accelerate the ions enough to maintain an ionized air gap.<br /> As the charged particles move through, the air, they are constantly recombining with other ions in the process of random motion, before being again knocked apart by an accelerated charge. Sparks produce light because when molecules recombine, they move to a lower energy state, and emit the difference in energy as a photon. These continual reactions produce a lot of heat, which cases the air gap to rapidly expand and make the sound we hear when a spark occurs.<br /> ==A Mathematical Model==<br /> <br /> What are the mathematical equations that allow us to model this topic. For example &lt;math&gt;{\frac{d\vec{p}}{dt}}_{system} = \vec{F}_{net}&lt;/math&gt; where '''p''' is the momentum of the system and '''F''' is the net force from the surroundings.<br /> <br /> ==History==<br /> Although it is well known that the greeks were aware of the phenomenon of electrical sparks, Leibniz formalized his observations of electric sparks in 1671. In 1716, Newton observes &quot;miniature sheet lightning&quot;. Franklin makes similar observations. In 1729, Gray discovers the conductivity of metals. In 1745, Haller reports that lightning tends to travel along metal objects, just like sparks. In 1749 Ben Franklin formalizes his idea for the experiment that would contribute his description of electricity, and in 1750 he suggests the idea for the lightning rod.<br /> ==Connectedness==<br /> <br /> ==References==<br /> [http://www.nuffieldfoundation.org/practical-physics/sparks-air] Nuffield Foundation: ''Sparks In Air''<br /> <br /> [http://www.physics.csbsju.edu/370/jcalvert/dischg.htm.html] Saint Benedict Saint John's University: Electrical Discharges<br /> <br /> [http://link.springer.com/article/10.1007%2FBF02017730] N. Kyzhanovsky: Mapping the History of Electricity<br /> <br /> <br /> ==References==<br /> <br /> This section contains the the references you used while writing this page<br /> <br /> [[Category:Which Category did you place this in?]]</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=12177 2015-12-04T17:57:58Z

<p>Brainmurphy: </p> <hr /> <div>The phenomenon of an electric field causing air to ionize such that the air emits light and sound is known as a spark. Sparks occur between two opposing charges, where the electric field between them is strong enough to cause the air molecules to split from their normally stable state, into positive and negative ions that can conduct current. <br /> <br /> ==The Physical Model==<br /> At a high level of abstraction, the occurrence of a spark is marked by three phases: the ionization of air particles, the propagation of the electric field in the air gap, and the neutralization of charges due to cancellation. These are no finite boundaries between these phases, although there is a general order to them, despite how quickly a spark occurs. <br /> ===Ionization of Air===<br /> In air, there is always some chance occurrence of ionized particles. However, air molecules (most notably Nitrogen and Oxygen) are very stable, so these ions do not make up a significant portion of all air molecules in our atmosphere. These stable molecules require a relatively large amount of energy to separate them from their electrons. Typically, collisions between air particles do not impart enough energy to ionize them -- separate them from some of their electrons.<br /> <br /> However, in the presence of a strong electric field, chance ions in the accelerate to very high speeds, gaining relatively large amounts of kinetic energy. In a strong enough electric field, these ions gain enough Kinetic energy to break apart air molecules when upon collision. The separation of the electrons from these air molecules creates two more ions: one negative (the electron) and one positive (the N2+ or O2+)<br /> ===Propagation of the Electric Field===<br /> Because electric fields are strongest near each of the two opposite charges, the chain reaction of ionization starts there. The new ions created through collisions with the ions accelerated by the electric field also accelerate due to the electric field. These new ions can then cause more air particles to ionize by striking them at high speeds. <br /> The negatively charged ions move towards the positively charged object that started the spark, and the positively charged ions move towards the negatively charged object. As this happens, the charge distribution in the air between the two charged objects changes. Before the spark began, the electric field emanated from the two charged objects. As ions begin to form, the electric field also emanates in part from the ionized air. This causes the electric field between the two charged object to become more uniform, much like what occurs in a wire when a circuit is closed.<br /> Eventually, the chain reactions coming from each charged object meet in the middle, and the &quot;circuit&quot; is complete.<br /> ===Neutralization of Charges===<br /> The molecules of the air are now sufficiently ionized to carry a current. The electrons in the gap move relatively rapidly toward the positively charged object, while the positive ions move very slowly towards the negatively charged object, due to the differences in their masses. As the ions hit the charged surfaces to which they are attracted, they combine with oppositely charged particles on that object's surface. When this happens, the charge on each object diminishes due to the cancellation of fields. Soon, there is no longer enough charge on the objects to accelerate the ions enough to maintain an ionized air gap.<br /> As the charged particles move through, the air, they are constantly recombining with other ions in the process of random motion, before being again knocked apart by an accelerated charge. Sparks produce light because when molecules recombine, they move to a lower energy state, and emit the difference in energy as a photon. These continual reactions produce a lot of heat, which cases the air gap to rapidly expand and make the sound we hear when a spark occurs.<br /> ==A Mathematical Model==<br /> <br /> What are the mathematical equations that allow us to model this topic. For example &lt;math&gt;{\frac{d\vec{p}}{dt}}_{system} = \vec{F}_{net}&lt;/math&gt; where '''p''' is the momentum of the system and '''F''' is the net force from the surroundings.<br /> <br /> ==History==<br /> Although it is well known that the greeks were aware of the phenomenon of electrical sparks, Leibniz formalized his observations of electric sparks in 1671[http://link.springer.com/article/10.1007%2FBF02017730]. In 1716, Newton observes &quot;miniature sheet lightning&quot;. Franklin makes similar observations[http://link.springer.com/article/10.1007%2FBF02017730]. In 1729, Gray discovers the conductivity of metals. In 1745, Haller reports that lightning tends to travel along metal objects, just like sparks[3]. In 1749 Ben Franklin formalizes his idea for the experiment that would contribute his description of electricity, and in 1750 he suggests the idea for the lightning rod[3].<br /> ==Connectedness==<br /> <br /> ==References==<br /> [http://www.nuffieldfoundation.org/practical-physics/sparks-air] Nuffield Foundation: ''Sparks In Air''<br /> <br /> [http://www.physics.csbsju.edu/370/jcalvert/dischg.htm.html] Saint Benedict Saint John's University: Electrical Discharges<br /> <br /> [http://link.springer.com/article/10.1007%2FBF02017730] N. Kyzhanovsky: Mapping the History of Electricity<br /> <br /> <br /> ==References==<br /> <br /> This section contains the the references you used while writing this page<br /> <br /> [[Category:Which Category did you place this in?]]</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=12135 2015-12-04T17:42:27Z

<p>Brainmurphy: </p> <hr /> <div>The phenomenon of an electric field causing air to ionize such that the air emits light and sound is known as a spark. Sparks occur between two opposing charges, where the electric field between them is strong enough to cause the air molecules to split from their normally stable state, into positive and negative ions that can conduct current. <br /> <br /> ==The Physical Model==<br /> At a high level of abstraction, the occurrence of a spark is marked by three phases: the ionization of air particles, the propagation of the electric field in the air gap, and the neutralization of charges due to cancellation. These are no finite boundaries between these phases, although there is a general order to them, despite how quickly a spark occurs. <br /> ===Ionization of Air===<br /> In air, there is always some chance occurrence of ionized particles. However, air molecules (most notably Nitrogen and Oxygen) are very stable, so these ions do not make up a significant portion of all air molecules in our atmosphere. These stable molecules require a relatively large amount of energy to separate them from their electrons. Typically, collisions between air particles do not impart enough energy to ionize them -- separate them from some of their electrons.<br /> <br /> However, in the presence of a strong electric field, chance ions in the accelerate to very high speeds, gaining relatively large amounts of kinetic energy. In a strong enough electric field, these ions gain enough Kinetic energy to break apart air molecules when upon collision. The separation of the electrons from these air molecules creates two more ions: one negative (the electron) and one positive (the N2+ or O2+)<br /> ===Propagation of the Electric Field===<br /> Because electric fields are strongest near each of the two opposite charges, the chain reaction of ionization starts there. The new ions created through collisions with the ions accelerated by the electric field also accelerate due to the electric field. These new ions can then cause more air particles to ionize by striking them at high speeds. <br /> The negatively charged ions move towards the positively charged object that started the spark, and the positively charged ions move towards the negatively charged object. As this happens, the charge distribution in the air between the two charged objects changes. Before the spark began, the electric field emanated from the two charged objects. As ions begin to form, the electric field also emanates in part from the ionized air. This causes the electric field between the two charged object to become more uniform, much like what occurs in a wire when a circuit is closed.<br /> Eventually, the chain reactions coming from each charged object meet in the middle, and the &quot;circuit&quot; is complete.<br /> ===Neutralization of Charges===<br /> The molecules of the air are now sufficiently ionized to carry a current. The electrons in the gap move relatively rapidly toward the positively charged object, while the positive ions move very slowly towards the negatively charged object, due to the differences in their masses. As the ions hit the charged surfaces to which they are attracted, they combine with oppositely charged particles on that object's surface. When this happens, the charge on each object diminishes due to the cancellation of fields. Soon, there is no longer enough charge on the objects to accelerate the ions enough to maintain an ionized air gap.<br /> As the charged particles move through, the air, they are constantly recombining with other ions in the process of random motion, before being again knocked apart by an accelerated charge. Sparks produce light because when molecules recombine, they move to a lower energy state, and emit the difference in energy as a photon. These continual reactions produce a lot of heat, which cases the air gap to rapidly expand and make the sound we hear when a spark occurs.<br /> ==A Mathematical Model==<br /> <br /> What are the mathematical equations that allow us to model this topic. For example &lt;math&gt;{\frac{d\vec{p}}{dt}}_{system} = \vec{F}_{net}&lt;/math&gt; where '''p''' is the momentum of the system and '''F''' is the net force from the surroundings.<br /> <br /> ==Connectedness==<br /> <br /> ==References==<br /> [http://www.nuffieldfoundation.org/practical-physics/sparks-air] Nuffield Foundation: ''Sparks In Air''<br /> <br /> [http://www.physics.csbsju.edu/370/jcalvert/dischg.htm.html] Saint Benedict Saint John's University: Electrical Discharges<br /> <br /> <br /> ==References==<br /> <br /> This section contains the the references you used while writing this page<br /> <br /> [[Category:Which Category did you place this in?]]</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=12127 2015-12-04T17:40:17Z

<p>Brainmurphy: </p> <hr /> <div>The phenomenon of an electric field causing air to ionize such that the air emits light and sound is known as a spark. Sparks occur between two opposing charges, where the electric field between them is strong enough to cause the air molecules to split from their normally stable state, into positive and negative ions that can conduct current. <br /> <br /> ==The Physical Model==<br /> At a high level of abstraction, the occurrence of a spark is marked by three phases: the ionization of air particles, the propagation of the electric field in the air gap, and the neutralization of charges due to cancellation. These are no finite boundaries between these phases, although there is a general order to them, despite how quickly a spark occurs. <br /> ===Ionization of Air===<br /> In air, there is always some chance occurrence of ionized particles. However, air molecules (most notably Nitrogen and Oxygen) are very stable, so these ions do not make up a significant portion of all air molecules in our atmosphere. These stable molecules require a relatively large amount of energy to separate them from their electrons. Typically, collisions between air particles do not impart enough energy to ionize them -- separate them from some of their electrons.<br /> <br /> However, in the presence of a strong electric field, chance ions in the accelerate to very high speeds, gaining relatively large amounts of kinetic energy. In a strong enough electric field, these ions gain enough Kinetic energy to break apart air molecules when upon collision. The separation of the electrons from these air molecules creates two more ions: one negative (the electron) and one positive (the N2+ or O2+)<br /> ===Propagation of the Electric Field===<br /> Because electric fields are strongest near each of the two opposite charges, the chain reaction of ionization starts there. The new ions created through collisions with the ions accelerated by the electric field also accelerate due to the electric field. These new ions can then cause more air particles to ionize by striking them at high speeds. <br /> The negatively charged ions move towards the positively charged object that started the spark, and the positively charged ions move towards the negatively charged object. As this happens, the charge distribution in the air between the two charged objects changes. Before the spark began, the electric field emanated from the two charged objects. As ions begin to form, the electric field also emanates in part from the ionized air. This causes the electric field between the two charged object to become more uniform, much like what occurs in a wire when a circuit is closed.<br /> Eventually, the chain reactions coming from each charged object meet in the middle, and the &quot;circuit&quot; is complete.<br /> ===Neutralization of Charges===<br /> The molecules of the air are now sufficiently ionized to carry a current. The electrons in the gap move relatively rapidly toward the positively charged object, while the positive ions move very slowly towards the negatively charged object, due to the differences in their masses. As the ions hit the charged surfaces to which they are attracted, they combine with oppositely charged particles on that object's surface. When this happens, the charge on each object diminishes due to the cancellation of fields. Soon, there is no longer enough charge on the objects to accelerate the ions enough to maintain an ionized air gap.<br /> As the charged particles move through, the air, they are constantly recombining with other ions in the process of random motion, before being again knocked apart by an accelerated charge. Sparks produce light because when molecules recombine, they move to a lower energy state, and emit the difference in energy as a photon. These continual reactions produce a lot of heat, which cases the air gap to rapidly expand and make the sound we hear when a spark occurs.<br /> ==A Mathematical Model==<br /> <br /> What are the mathematical equations that allow us to model this topic. For example &lt;math&gt;{\frac{d\vec{p}}{dt}}_{system} = \vec{F}_{net}&lt;/math&gt; where '''p''' is the momentum of the system and '''F''' is the net force from the surroundings.<br /> <br /> ==Connectedness==<br /> <br /> <br /> ===External links===<br /> [http://www.nuffieldfoundation.org/practical-physics/sparks-air] Nuffield Foundation: ''Sparks In Air''<br /> <br /> [http://www.physics.csbsju.edu/370/jcalvert/dischg.htm.html] Saint Benedict Saint John's University: Electrical Discharges<br /> <br /> <br /> ==References==<br /> <br /> This section contains the the references you used while writing this page<br /> <br /> [[Category:Which Category did you place this in?]]</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=12126 2015-12-04T17:39:57Z

<p>Brainmurphy: </p> <hr /> <div>The phenomenon of an electric field causing air to ionize such that the air emits light and sound is known as a spark. Sparks occur between two opposing charges, where the electric field between them is strong enough to cause the air molecules to split from their normally stable state, into positive and negative ions that can conduct current. <br /> <br /> ==The Physical Model==<br /> At a high level of abstraction, the occurrence of a spark is marked by three phases: the ionization of air particles, the propagation of the electric field in the air gap, and the neutralization of charges due to cancellation. These are no finite boundaries between these phases, although there is a general order to them, despite how quickly a spark occurs. <br /> ===Ionization of Air===<br /> In air, there is always some chance occurrence of ionized particles. However, air molecules (most notably Nitrogen and Oxygen) are very stable, so these ions do not make up a significant portion of all air molecules in our atmosphere. These stable molecules require a relatively large amount of energy to separate them from their electrons. Typically, collisions between air particles do not impart enough energy to ionize them -- separate them from some of their electrons.<br /> <br /> However, in the presence of a strong electric field, chance ions in the accelerate to very high speeds, gaining relatively large amounts of kinetic energy. In a strong enough electric field, these ions gain enough Kinetic energy to break apart air molecules when upon collision. The separation of the electrons from these air molecules creates two more ions: one negative (the electron) and one positive (the N2+ or O2+)<br /> ===Propagation of the Electric Field===<br /> Because electric fields are strongest near each of the two opposite charges, the chain reaction of ionization starts there. The new ions created through collisions with the ions accelerated by the electric field also accelerate due to the electric field. These new ions can then cause more air particles to ionize by striking them at high speeds. <br /> The negatively charged ions move towards the positively charged object that started the spark, and the positively charged ions move towards the negatively charged object. As this happens, the charge distribution in the air between the two charged objects changes. Before the spark began, the electric field emanated from the two charged objects. As ions begin to form, the electric field also emanates in part from the ionized air. This causes the electric field between the two charged object to become more uniform, much like what occurs in a wire when a circuit is closed.<br /> Eventually, the chain reactions coming from each charged object meet in the middle, and the &quot;circuit&quot; is complete.<br /> ===Neutralization of Charges===<br /> The molecules of the air are now sufficiently ionized to carry a current. The electrons in the gap move relatively rapidly toward the positively charged object, while the positive ions move very slowly towards the negatively charged object, due to the differences in their masses. As the ions hit the charged surfaces to which they are attracted, they combine with oppositely charged particles on that object's surface. When this happens, the charge on each object diminishes due to the cancellation of fields. Soon, there is no longer enough charge on the objects to accelerate the ions enough to maintain an ionized air gap.<br /> As the charged particles move through, the air, they are constantly recombining with other ions in the process of random motion, before being again knocked apart by an accelerated charge. Sparks produce light because when molecules recombine, they move to a lower energy state, and emit the difference in energy as a photon. These continual reactions produce a lot of heat, which cases the air gap to rapidly expand and make the sound we hear when a spark occurs.<br /> ==A Mathematical Model==<br /> <br /> What are the mathematical equations that allow us to model this topic. For example &lt;math&gt;{\frac{d\vec{p}}{dt}}_{system} = \vec{F}_{net}&lt;/math&gt; where '''p''' is the momentum of the system and '''F''' is the net force from the surroundings.<br /> <br /> ==Connectedness==<br /> <br /> <br /> ===External links===<br /> [http://www.nuffieldfoundation.org/practical-physics/sparks-air] Nuffield Foundation: ''Sparks In Air''<br /> [http://www.physics.csbsju.edu/370/jcalvert/dischg.htm.html] Saint Benedict Saint John's University: Electrical Discharges<br /> <br /> <br /> ==References==<br /> <br /> This section contains the the references you used while writing this page<br /> <br /> [[Category:Which Category did you place this in?]]</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=12100 2015-12-04T17:35:21Z

<p>Brainmurphy: </p> <hr /> <div>The phenomenon of an electric field causing air to ionize such that the air emits light and sound is known as a spark. Sparks occur between two opposing charges, where the electric field between them is strong enough to cause the air molecules to split from their normally stable state, into positive and negative ions that can conduct current. <br /> <br /> ==The Physical Model==<br /> At a high level of abstraction, the occurrence of a spark is marked by three phases: the ionization of air particles, the propagation of the electric field in the air gap, and the neutralization of charges due to cancellation. These are no finite boundaries between these phases, although there is a general order to them, despite how quickly a spark occurs. <br /> ===Ionization of Air===<br /> In air, there is always some chance occurrence of ionized particles. However, air molecules (most notably Nitrogen and Oxygen) are very stable, so these ions do not make up a significant portion of all air molecules in our atmosphere. These stable molecules require a relatively large amount of energy to separate them from their electrons. Typically, collisions between air particles do not impart enough energy to ionize them -- separate them from some of their electrons.<br /> <br /> However, in the presence of a strong electric field, chance ions in the accelerate to very high speeds, gaining relatively large amounts of kinetic energy. In a strong enough electric field, these ions gain enough Kinetic energy to break apart air molecules when upon collision. The separation of the electrons from these air molecules creates two more ions: one negative (the electron) and one positive (the N2+ or O2+)<br /> ===Propagation of the Electric Field===<br /> Because electric fields are strongest near each of the two opposite charges, the chain reaction of ionization starts there. The new ions created through collisions with the ions accelerated by the electric field also accelerate due to the electric field. These new ions can then cause more air particles to ionize by striking them at high speeds. <br /> The negatively charged ions move towards the positively charged object that started the spark, and the positively charged ions move towards the negatively charged object. As this happens, the charge distribution in the air between the two charged objects changes. Before the spark began, the electric field emanated from the two charged objects. As ions begin to form, the electric field also emanates in part from the ionized air. This causes the electric field between the two charged object to become more uniform, much like what occurs in a wire when a circuit is closed.<br /> Eventually, the chain reactions coming from each charged object meet in the middle, and the &quot;circuit&quot; is complete.<br /> ===Neutralization of Charges===<br /> The molecules of the air are now sufficiently ionized to carry a current. The electrons in the gap move relatively rapidly toward the positively charged object, while the positive ions move very slowly towards the negatively charged object, due to the differences in their masses. As the ions hit the charged surfaces to which they are attracted, they combine with oppositely charged particles on that object's surface. When this happens, the charge on each object diminishes due to the cancellation of fields. Soon, there is no longer enough charge on the objects to accelerate the ions enough to maintain an ionized air gap.<br /> As the charged particles move through, the air, they are constantly recombining with other ions in the process of random motion, before being again knocked apart by an accelerated charge. Sparks produce light because when molecules recombine, they move to a lower energy state, and emit the difference in energy as a photon. These continual reactions produce a lot of heat, which cases the air gap to rapidly expand and make the sound we hear when a spark occurs.<br /> ==A Mathematical Model==<br /> <br /> What are the mathematical equations that allow us to model this topic. For example &lt;math&gt;{\frac{d\vec{p}}{dt}}_{system} = \vec{F}_{net}&lt;/math&gt; where '''p''' is the momentum of the system and '''F''' is the net force from the surroundings.<br /> <br /> ==Connectedness==<br /> <br /> <br /> ===External links===<br /> [http://www.scientificamerican.com/article/bring-science-home-reaction-time/]<br /> <br /> <br /> ==References==<br /> <br /> This section contains the the references you used while writing this page<br /> <br /> [[Category:Which Category did you place this in?]]</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=12071 2015-12-04T17:24:44Z

<p>Brainmurphy: </p> <hr /> <div>The phenomenon of an electric field causing air to ionize such that the air emits light and sound is known as a spark. Sparks occur between two opposing charges, where the electric field between them is strong enough to cause the air molecules to split from their normally stable state, into positive and negative ions that can conduct current. <br /> <br /> ==The Physical Model==<br /> At a high level of abstraction, the occurrence of a spark is marked by three phases: the ionization of air particles, the propagation of the electric field in the air gap, and the neutralization of charges due to cancellation. These are no finite boundaries between these phases, although there is a general order to them, despite how quickly a spark occurs. <br /> ===Ionization of Air===<br /> In air, there is always some chance occurrence of ionized particles. However, air molecules (most notably Nitrogen and Oxygen) are very stable, so these ions do not make up a significant portion of all air molecules in our atmosphere. These stable molecules require a relatively large amount of energy to separate them from their electrons. Typically, collisions between air particles do not impart enough energy to ionize them -- separate them from some of their electrons.<br /> <br /> However, in the presence of a strong electric field, chance ions in the accelerate to very high speeds, gaining relatively large amounts of kinetic energy. In a strong enough electric field, these ions gain enough Kinetic energy to break apart air molecules when upon collision. The separation of the electrons from these air molecules creates two more ions: one negative (the electron) and one positive (the N2+ or O2+)<br /> ===Propagation of the Electric Field===<br /> Because electric fields are strongest near each of the two opposite charges, the chain reaction of ionization starts there. The new ions created through collisions with the ions accelerated by the electric field also accelerate due to the electric field. These new ions can then cause more air particles to ionize by striking them at high speeds. <br /> The negatively charged ions move towards the positively charged object that started the spark, and the positively charged ions move towards the negatively charged object. As this happens, the charge distribution in the air between the two charged objects changes. Before the spark began, the electric field emanated from the two charged objects. As ions begin to form, the electric field also emanates in part from the ionized air. This causes the electric field between the two charged object to become more uniform, much like what occurs in a wire when a circuit is closed.<br /> Eventually, the chain reactions coming from each charged object meet in the middle, and the &quot;circuit&quot; is complete.<br /> ===Neutralization of Charges===<br /> The molecules of the air are now sufficiently ionized to carry a current. The electrons in the gap move relatively rapidly toward the positively charged object, while the positive ions move very slowly towards the negatively charged object, due to the differences in their masses. As the ions hit the charged surfaces to which they are attracted, they combine with oppositely charged particles on that object's surface. When this happens, the charge on each object diminishes due to the cancellation of fields. Soon, there is no longer enough charge on the objects to accelerate the ions enough to maintain an ionized air gap.<br /> As the charged particles move through, the air, they are constantly recombining with other ions in the process of random motion, before being again knocked apart by an accelerated charge. Sparks produce light because when molecules recombine, they move to a lower energy state, and emit the difference in energy as a photon. These continual reactions produce a lot of heat, which cases the air gap to rapidly expand and make the sound we hear when a spark occurs.<br /> ==A Mathematical Model==<br /> <br /> What are the mathematical equations that allow us to model this topic. For example &lt;math&gt;{\frac{d\vec{p}}{dt}}_{system} = \vec{F}_{net}&lt;/math&gt; where '''p''' is the momentum of the system and '''F''' is the net force from the surroundings.<br /> <br /> ==Connectedness==</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=12058 2015-12-04T17:17:40Z

<p>Brainmurphy: </p> <hr /> <div>The phenomenon of an electric field causing air to ionize such that the air emits light and sound is known as a spark. Sparks occur between two opposing charges, where the electric field between them is strong enough to cause the air molecules to split from their normally stable state, into positive and negative ions that can conduct current. <br /> <br /> ==The Physical Model==<br /> At a high level of abstraction, the occurrence of a spark is marked by three phases: the ionization of air particles, the propagation of the electric field in the air gap, and the neutralization of charges due to cancellation. These are no finite boundaries between these phases, although there is a general order to them, despite how quickly a spark occurs. <br /> ===Ionization of Air===<br /> In air, there is always some chance occurrence of ionized particles. However, air molecules (most notably Nitrogen and Oxygen) are very stable, so these ions do not make up a significant portion of all air molecules in our atmosphere. These stable molecules require a relatively large amount of energy to separate them from their electrons. Typically, collisions between air particles do not impart enough energy to ionize them -- separate them from some of their electrons.<br /> <br /> However, in the presence of a strong electric field, chance ions in the accelerate to very high speeds, gaining relatively large amounts of kinetic energy. In a strong enough electric field, these ions gain enough Kinetic energy to break apart air molecules when upon collision. The separation of the electrons from these air molecules creates two more ions: one negative (the electron) and one positive (the N2+ or O2+)<br /> ===Propagation of the Electric Field===<br /> Because electric fields are strongest near each of the two opposite charges, the chain reaction of ionization starts there. The new ions created through collisions with the ions accelerated by the electric field also accelerate due to the electric field. These new ions can then cause more air particles to ionize by striking them at high speeds. <br /> The negatively charged ions move towards the positively charged object that started the spark, and the positively charged ions move towards the negatively charged object. As this happens, the charge distribution in the air between the two charged objects changes. Before the spark began, the electric field emanated from the two charged objects. As ions begin to form, the electric field also emanates in part from the ionized air. This causes the electric field between the two charged object to become more uniform, much like what occurs in a wire when a circuit is closed.<br /> Eventually, the chain reactions coming from each charged object meet in the middle, and the &quot;circuit&quot; is complete.<br /> ===Neutralization of Charges===<br /> The molecules of the air are now sufficiently ionized to carry a current. The electrons in the gap move relatively rapidly toward the positively charged object, while the positive ions move very slowly towards the negatively charged object, due to the differences in their masses. As the ions hit the charged surfaces to which they are attracted, they combine with oppositely charged particles on that object's surface. When this happens, the charge on each object diminishes due to the cancellation of fields. Soon, there is no longer enough charge on the objects to accelerate the ions enough to maintain an ionized air gap.<br /> As the charged particles move through, the air, they are constantly recombining with other ions in the process of random motion, before being again knocked apart by an accelerated charge. Sparks produce light because when molecules recombine, they move to a lower energy state, and emit the difference in energy as a photon. These continual reactions produce a lot of heat, which cases the air gap to rapidly expand and make the sound we hear when a spark occurs.<br /> ===A Mathematical Model===<br /> <br /> What are the mathematical equations that allow us to model this topic. For example &lt;math&gt;{\frac{d\vec{p}}{dt}}_{system} = \vec{F}_{net}&lt;/math&gt; where '''p''' is the momentum of the system and '''F''' is the net force from the surroundings.<br /> <br /> ===A Computational Model===<br /> <br /> How do we visualize or predict using this topic. Consider embedding some vpython code here [https://trinket.io/glowscript/31d0f9ad9e Teach hands-on with GlowScript]<br /> <br /> ==Examples==<br /> <br /> Be sure to show all steps in your solution and include diagrams whenever possible<br /> <br /> ===Simple===<br /> ===Middling===<br /> ===Difficult===<br /> <br /> ==Connectedness==</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=11304 2015-12-04T03:26:50Z

<p>Brainmurphy: </p> <hr /> <div>The phenomenon of an electric field causing air to ionize such that the air emits light and sound is known as a spark. Sparks occur between two opposing charges, where the electric field between them is strong enough to cause the air molecules to split from their normally stable state, into positive and negative ions that can conduct current. <br /> <br /> ==The Physical Model==<br /> At a high level of abstraction, the occurrence of a spark is marked by three phases: the ionization of air particles, the propagation of the electric field in the air gap, and the neutralization of charges due to cancellation. These are no finite boundaries between these phases, although there is a general order to them, despite how quickly a spark occurs. <br /> ===Ionization of Air===<br /> In air, there is always some chance occurrence of ionized particles. However, air molecules (most notably Nitrogen and Oxygen) are very stable, so these ions do not make up a significant portion of all air molecules in our atmosphere. These stable molecules require a relatively large amount of energy to separate them from their electrons. Typically, collisions between air particles do not impart enough energy to ionize them -- separate them from some of their electrons.<br /> <br /> However, in the presence of a strong electric field, chance ions in the accelerate to very high speeds, gaining relatively large amounts of kinetic energy. In a strong enough electric field, these ions gain enough Kinetic energy to break apart air molecules when upon collision. The separation of the electrons from these air molecules creates two more ions: one negative (the electron) and one positive (the N2+ or O2+)<br /> ===Propagation of the Electric Field===<br /> Because electric fields are strongest near each of the two opposite charges, the chain reaction of ionization starts there. The new ions created through collisions with the ions accelerated by the electric field also accelerate due to the electric field. These new ions can then cause more air particles to ionize by striking them at high speeds. <br /> The negatively charged ions move towards the positively charged object that started the spark, and the positively charged ions move towards the negatively charged object. As this happens, the charge distribution in the air between the two charged objects changes. Before the spark began, the electric field emanated from the two charged objects. As ions begin to form, the electric field also emanates in part from the ionized air. This causes the electric field between the two charged object to become more uniform, much like when a switch is closed on a circuit. <br /> Eventually, the chain reactions coming from each charged object meet in the middle, and the &quot;circuit&quot; is complete.<br /> ===A Mathematical Model===<br /> <br /> What are the mathematical equations that allow us to model this topic. For example &lt;math&gt;{\frac{d\vec{p}}{dt}}_{system} = \vec{F}_{net}&lt;/math&gt; where '''p''' is the momentum of the system and '''F''' is the net force from the surroundings.<br /> <br /> ===A Computational Model===<br /> <br /> How do we visualize or predict using this topic. Consider embedding some vpython code here [https://trinket.io/glowscript/31d0f9ad9e Teach hands-on with GlowScript]<br /> <br /> ==Examples==<br /> <br /> Be sure to show all steps in your solution and include diagrams whenever possible<br /> <br /> ===Simple===<br /> ===Middling===<br /> ===Difficult===<br /> <br /> ==Connectedness==</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=11149 2015-12-04T01:44:52Z

<p>Brainmurphy: </p> <hr /> <div>'''''In progress'''''--[[User:Brainmurphy|Brainmurphy]] ([[User talk:Brainmurphy|talk]]) 11:43, 4 November 2015 (EST)<br /> ==The Main Idea==<br /> <br /> The phenomenon of an electric field causing air to ionize such that the air emits light and sound is known as a spark. Sparks occur between two opposing charges, where the electric field between them is strong enough to cause the air molecules to split from their normally stable state, into positive and negative ions that can conduct current. <br /> ===A Mathematical Model===<br /> <br /> What are the mathematical equations that allow us to model this topic. For example &lt;math&gt;{\frac{d\vec{p}}{dt}}_{system} = \vec{F}_{net}&lt;/math&gt; where '''p''' is the momentum of the system and '''F''' is the net force from the surroundings.<br /> <br /> ===A Computational Model===<br /> <br /> How do we visualize or predict using this topic. Consider embedding some vpython code here [https://trinket.io/glowscript/31d0f9ad9e Teach hands-on with GlowScript]<br /> <br /> ==Examples==<br /> <br /> Be sure to show all steps in your solution and include diagrams whenever possible<br /> <br /> ===Simple===<br /> ===Middling===<br /> ===Difficult===<br /> <br /> ==Connectedness==</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=458 2015-11-04T16:43:31Z

<p>Brainmurphy: </p> <hr /> <div>'''''In progress'''''--[[User:Brainmurphy|Brainmurphy]] ([[User talk:Brainmurphy|talk]]) 11:43, 4 November 2015 (EST)<br /> ==The Main Idea==<br /> <br /> State, in your own words, the main idea for this topic<br /> Electric Field of Capacitor<br /> <br /> ===A Mathematical Model===<br /> <br /> What are the mathematical equations that allow us to model this topic. For example &lt;math&gt;{\frac{d\vec{p}}{dt}}_{system} = \vec{F}_{net}&lt;/math&gt; where '''p''' is the momentum of the system and '''F''' is the net force from the surroundings.<br /> <br /> ===A Computational Model===<br /> <br /> How do we visualize or predict using this topic. Consider embedding some vpython code here [https://trinket.io/glowscript/31d0f9ad9e Teach hands-on with GlowScript]<br /> <br /> ==Examples==<br /> <br /> Be sure to show all steps in your solution and include diagrams whenever possible<br /> <br /> ===Simple===<br /> ===Middling===<br /> ===Difficult===<br /> <br /> ==Connectedness==</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Sparks_in_Air&diff=457 2015-11-04T16:42:21Z

<p>Brainmurphy: Created page with &quot;Short Description of Topic ==The Main Idea== State, in your own words, the main idea for this topic Electric Field of Capacitor ===A Mathematical Model=== What are the mat...&quot;</p> <hr /> <div>Short Description of Topic<br /> <br /> ==The Main Idea==<br /> <br /> State, in your own words, the main idea for this topic<br /> Electric Field of Capacitor<br /> <br /> ===A Mathematical Model===<br /> <br /> What are the mathematical equations that allow us to model this topic. For example &lt;math&gt;{\frac{d\vec{p}}{dt}}_{system} = \vec{F}_{net}&lt;/math&gt; where '''p''' is the momentum of the system and '''F''' is the net force from the surroundings.<br /> <br /> ===A Computational Model===<br /> <br /> How do we visualize or predict using this topic. Consider embedding some vpython code here [https://trinket.io/glowscript/31d0f9ad9e Teach hands-on with GlowScript]<br /> <br /> ==Examples==<br /> <br /> Be sure to show all steps in your solution and include diagrams whenever possible<br /> <br /> ===Simple===<br /> ===Middling===<br /> ===Difficult===<br /> <br /> ==Connectedness==</div>

Brainmurphy http://www.physicsbook.gatech.edu/index.php?title=Main_Page&diff=456 2015-11-04T16:41:25Z

<p>Brainmurphy: /* Fields */</p> <hr /> <div>__NOTOC__<br /> Welcome to the Georgia Tech Wiki for Intro Physics. This resources was created so that students can contribute and curate content to help those with limited or no access to a textbook. When reading this website, please correct any errors you may come across. If you read something that isn't clear, please consider revising it!<br /> <br /> Looking to make a contribution?<br /> #Pick a specific topic from intro physics<br /> #Add that topic, as a link to a new page, under the appropriate category listed below by editing this page.<br /> #Copy and paste the default [[Template]] into your new page and start editing.<br /> <br /> Please remember that this is not a textbook and you are not limited to expressing your ideas with only text and equations. Whenever possible embed: pictures, videos, diagrams, simulations, computational models (e.g. Glowscript), and whatever content you think makes learning physics easier for other students.<br /> <br /> == Source Material ==<br /> All of the content added to this resource must be in the public domain or similar free resource. If you are unsure about a source, contact the original author for permission. That said, there is a surprisingly large amount of introductory physics content scattered across the web. Here is an incomplete list of intro physics resources (please update as needed).<br /> * A physics resource written by experts for an expert audience [https://en.wikipedia.org/wiki/Portal:Physics Physics Portal]<br /> * A wiki book on modern physics [https://en.wikibooks.org/wiki/Modern_Physics Modern Physics Wiki]<br /> * The MIT open courseware for intro physics [http://ocw.mit.edu/resources/res-8-002-a-wikitextbook-for-introductory-mechanics-fall-2009/index.htm MITOCW Wiki]<br /> * An online concept map of intro physics [http://hyperphysics.phy-astr.gsu.edu/hbase/hph.html HyperPhysics]<br /> * Interactive physics simulations [https://phet.colorado.edu/en/simulations/category/physics PhET]<br /> * OpenStax algebra based intro physics textbook [https://openstaxcollege.org/textbooks/college-physics College Physics]<br /> * The Open Source Physics project is a collection of online physics resources [http://www.opensourcephysics.org/ OSP]<br /> * A resource guide compiled by the [http://www.aapt.org/ AAPT] for educators [http://www.compadre.org/ ComPADRE]<br /> <br /> == Organizing Catagories ==<br /> These are the broad, overarching categories, that we cover in two semester of introductory physics. You can add subcategories or make a new category as needed. A single topic should direct readers to a page in one of these catagories.<br /> <br /> &lt;div class=&quot;toccolours mw-collapsible mw-collapsed&quot;&gt;<br /> ===Interactions===<br /> &lt;div class=&quot;mw-collapsible-content&quot;&gt;<br /> *[[Fundamental Interactions]] <br /> *[[System &amp; Surroundings]] <br /> <br /> &lt;/div&gt;<br /> &lt;/div&gt;<br /> <br /> &lt;div class=&quot;toccolours mw-collapsible mw-collapsed&quot;&gt;<br /> <br /> ===Theory===<br /> &lt;div class=&quot;mw-collapsible-content&quot;&gt;<br /> *[[Einstein's Theory of Relativity]]<br /> &lt;/div&gt;<br /> &lt;/div&gt;<br /> <br /> &lt;div class=&quot;toccolours mw-collapsible mw-collapsed&quot;&gt;<br /> <br /> ===Notable Scientists===<br /> &lt;div class=&quot;mw-collapsible-content&quot;&gt;<br /> *[[Albert Einstein]]<br /> &lt;/div&gt;<br /> &lt;/div&gt;<br /> <br /> &lt;div class=&quot;toccolours mw-collapsible mw-collapsed&quot;&gt;<br /> <br /> ===Properties of Matter===<br /> &lt;div class=&quot;mw-collapsible-content&quot;&gt;<br /> *[[Mass]]<br /> *[[Charge]]<br /> *[[Spin]]<br /> *[[SI Units]]<br /> &lt;/div&gt;<br /> &lt;/div&gt;<br /> <br /> &lt;div class=&quot;toccolours mw-collapsible mw-collapsed&quot;&gt;<br /> <br /> ===Contact Interactions===<br /> &lt;div class=&quot;mw-collapsible-content&quot;&gt;<br /> * [[Young's Modulus]]<br /> * [[Friction]]<br /> * [[Tension]]<br /> &lt;/div&gt;<br /> &lt;/div&gt;<br /> <br /> &lt;div class=&quot;toccolours mw-collapsible mw-collapsed&quot;&gt;<br /> <br /> ===Momentum===<br /> &lt;div class=&quot;mw-collapsible-content&quot;&gt;<br /> * [[Vectors]]<br /> * [[Kinematics]]<br /> * Predicting Change in one dimension<br /> * [[Predicting Change in multiple dimensions]]<br /> * [[Momentum Principle]]<br /> &lt;/div&gt;<br /> &lt;/div&gt;<br /> <br /> &lt;div class=&quot;toccolours mw-collapsible mw-collapsed&quot;&gt;<br /> <br /> ===Angular Momentum===<br /> &lt;div class=&quot;mw-collapsible-content&quot;&gt;<br /> * [[The Moments of Inertia]]<br /> * [[Rotation]]<br /> * [[Torque]]<br /> * Predicting a Change in Rotation<br /> &lt;/div&gt;<br /> &lt;/div&gt;<br /> <br /> &lt;div class=&quot;toccolours mw-collapsible mw-collapsed&quot;&gt;<br /> <br /> ===Energy===<br /> &lt;div class=&quot;mw-collapsible-content&quot;&gt;<br /> *Predicting Change<br /> *[[Rest Mass Energy]]<br /> *[[Kinetic Energy]]<br /> *[[Potential Energy]]<br /> *[[Work]]<br /> *[[Thermal Energy]]<br /> *[[Conservation of Energy]]<br /> &lt;/div&gt;<br /> &lt;/div&gt;<br /> <br /> &lt;div class=&quot;toccolours mw-collapsible mw-collapsed&quot;&gt;<br /> <br /> ===Fields===<br /> &lt;div class=&quot;mw-collapsible-content&quot;&gt;<br /> * [[Electric Field]] of a<br /> ** [[Point Charge]]<br /> ** [[Electric Dipole]]<br /> ** [[Capacitor]]<br /> ** [[Charged Rod]]<br /> ** [[Charged Disk]]<br /> ** [[Charged Spherical Shell]]<br /> *[[Electric Potential]] <br /> **[[Potential Difference in a Uniform Field]]<br /> *[[Magnetic Field]]<br /> **[[Direction of Magnetic Field]]<br /> **[[Bar Magnet]]<br /> **[[Magnetic Force]]<br /> **[[Hall Effect]]<br /> **[[Lorentz Force]]<br /> **[[Biot-Savart Law]]<br /> **[[Integration Techniques for Magnetic Field]]<br /> **[[Sparks in Air]]<br /> &lt;/div&gt;<br /> &lt;/div&gt;<br /> <br /> &lt;div class=&quot;toccolours mw-collapsible mw-collapsed&quot;&gt;<br /> <br /> ===Simple Circuits===<br /> &lt;div class=&quot;mw-collapsible-content&quot;&gt;<br /> *[[Components]]<br /> *[[Steady State]]<br /> *[[Non Steady State]]<br /> *[[Node Rule]]<br /> *[[Loop Rule]]<br /> *[[Power in a circuit]]<br /> *[[Ammeters,Voltmeters,Ohmmeters]]<br /> *[[Current]]<br /> *[[Ohm's Law]]<br /> &lt;/div&gt;<br /> &lt;/div&gt;<br /> <br /> &lt;div class=&quot;toccolours mw-collapsible mw-collapsed&quot;&gt;<br /> <br /> ===Maxwell's Equations===<br /> &lt;div class=&quot;mw-collapsible-content&quot;&gt;<br /> *[[Gauss's Flux Theorem]]<br /> **[[Electric Fields]]<br /> **[[Magnetic Fields]]<br /> *[[Faraday's Law]]<br /> *[[Ampere-Maxwell Law]]<br /> &lt;/div&gt;<br /> &lt;/div&gt;<br /> <br /> &lt;div class=&quot;toccolours mw-collapsible mw-collapsed&quot;&gt;<br /> <br /> ===Radiation===<br /> &lt;div class=&quot;mw-collapsible-content&quot;&gt;<br /> &lt;/div&gt;<br /> &lt;/div&gt;<br /> <br /> == Resources ==<br /> * Commonly used wiki commands [https://en.wikipedia.org/wiki/Help:Cheatsheet Wiki Cheatsheet]<br /> * A guide to representing equations in math mode [https://en.wikipedia.org/wiki/Help:Displaying_a_formula Wiki Math Mode]<br /> * A page to keep track of all the physics [[Constants]]<br /> * An overview of [[VPython]]</div>

Brainmurphy