Physics Book - User contributions [en]

Electromagnetic Spectrum

2015-12-05T19:39:28Z

Croberts65:

This page has been created and claimed by Clayton Roberts (Croberts65)

The electromagnetic spectrum describes all different frequencies of light that can be observed, and is most commonly associated with the visible chromatic colors.

==The Main Idea==

The frequency in Hertz (Hz) of electromagnetic waves can be related to the energy and color (if applicable) of the type of electromagnetic radiation. This can be used in chemistry for ionization, among other fields of science where the material and relative temperature can be related.

===A Mathematical Model===

<math>v = {\frac{c}{\lambda}}</math>
where
*<math>v</math> is the frequency of the electromagnetic wave in Hertz (Hz) or number of cycles a second and can also be written as "<math>f</math>"
*<math>c</math> is the speed of light ( <math>2.998 \times 10^8 \frac{m}{s}</math> )
*<math>\lambda</math> is the wavelength in meters

<math>E = \sqrt {\frac{P/A}{c \times \epsilon_{0}}}</math>
where
*<math>E</math> is the magnitude of the electric field in Newtons per Columb (N/C)
*<math>P</math> is the power output of the beam of electromagnetic waves in Watts (W)
*<math>A</math> is the area of the beam in meters squared ( <math>m^{2}</math> )
*<math>\epsilon_{0}</math> is the vacuum permittivity constant ( <math>8.85 \times 10^{-12}</math> )
*<math>c</math> is the speed of light ( <math>2.998 \times 10^8 \frac{m}{s}</math> )

===A Visual Model===

[[File:Spectrum.png|700 px]]

==Examples==

===Simple===
What type of electromagnetic wave has a higher frequency, ultraviolet or infrared?

A. Ultraviolet

===Middling===
Calculate the frequency of violet light (450 nm).

1. <math>v = {\frac{c}{\lambda}}</math>

2. <math>450 \times 10^{-9} = \frac {2.998 \times 10^8}{\lambda}</math>

3. <math>\frac {1}{\lambda} = \frac {450 \times 10^{-9}}{2.998 \times 10^8} = 1.501 \times 10^{-15}</math>

4. <math>\lambda = 6.662 \times 10^{14}</math> Hz

===Difficult===
A small laser used as a pointer produces a beam of red light 2 mm in diameter, and has a power output of 4 milliwatts. What is the magnitude of the electric field in the laser beam?

1. <math>E = \sqrt {\frac{P/A}{c \times \epsilon_{0}}}</math>

2. <math>E = \sqrt { \frac{(4 \times 10^{-3}) / ((2/2) \pi \times 10^{-3 + -3})}{(2.998 \times 10^{8}) \times (8.85 \times 10^{-12})} }</math>

3. <math>E = \sqrt { \frac{4 \times 10^{3}}{2.65 \pi \times 10^{-3}} }</math>

4. <math>E = \sqrt {4.80 \times 10^5} = 6.93 \times 10^{2}</math>

==Interaction With Matter==

*Micro Waves - cause forces on molecules that cause torsion and rotation, causing friction in more strongly interconnected molecules, like food and other solids; this is why food heats up in a microwave oven
*Infrared Waves - causes molecular vibration, basically, this is what heat lamps produce, which is why the air gets hot around the lamp
*Visible Light - can produce ionization, but really acts more like infrared waves than ultraviolet waves
*Ultraviolet Waves - causes molecular ionization, but doesn't move the molecule around; this is why you get sunburned, because the ultraviolet light is destroying your skin

==History==

The first time that a part of the electromagnetic spectrum was observed was in 1800, when scientist William Herschel was looking at light from a heated object through a prism. He noticed that the light surpassed the color red, into what we now know today as the infrared frequency of light. Some years later in 1845, Micheal Faraday made the connection between light and electromagnetism, when he observed that polarized light responded to a magnet. James Maxwell made the final step, when he realized that electromagnetic waves must travel at the speed of light.

==Connectedness==
The electromagnetic spectrum is used for a variety of things including
*Cooking (microwaves)
*Radio and Communication
*Radar
*Military Defense
*Environmental Impacts (ultraviolet light)
*Medical Treatments (gamma rays, x-rays)
*Nuclear Physics
*The sense of sight

==References & Further Reading==

[[http://en.wikipedia.org/wiki/Electromagnetic_spectrum Electromagnetic Spectrum]][[http://www.school-for-champions.com/science/electromagnetic_spectrum.htm#.VmKF7TZllsM 2]]

[[http://en.wikipedia.org/wiki/Vacuum_permittivity Vacuum Permittivity]]

[[http://en.wikipedia.org/wiki/Electric_field Electric Field]]

[[http://revisionworld.com/gcse-revision/physics/waves/uses-electromagnetic-waves Uses of Electromagnetic Waves]]

[[Category:Waves]]

Electromagnetic Spectrum

2015-12-05T07:16:54Z

Croberts65:

This page has been created and claimed by Clayton Roberts (Croberts65)

The electromagnetic spectrum describes all different frequencies of light that can be observed, and is most commonly associated with the visible chromatic colors.

==The Main Idea==

The frequency in Hertz (Hz) of electromagnetic waves can be related to the energy and color (if applicable) of the type of electromagnetic radiation. This can be used in chemistry for ionization, among other fields of science where the material and relative temperature can be related.

===A Mathematical Model===

<math>v = {\frac{c}{\lambda}}</math>
where
*<math>v</math> is the frequency of the electromagnetic wave in Hertz (Hz) or number of cycles a second and can also be written as "<math>f</math>"
*<math>c</math> is the speed of light ( <math>2.998 \times 10^8 \frac{m}{s}</math> )
*<math>\lambda</math> is the wavelength in meters

<math>E = \sqrt {\frac{P/A}{c \times \epsilon_{0}}}</math>
where
*<math>E</math> is the magnitude of the electric field in Newtons per Columb (N/C)
*<math>P</math> is the power output of the beam of electromagnetic waves in Watts (W)
*<math>A</math> is the area of the beam in meters squared ( <math>m^{2}</math> )
*<math>\epsilon_{0}</math> is the vacuum permittivity constant ( <math>8.85 \times 10^{-12}</math> )
*<math>c</math> is the speed of light ( <math>2.998 \times 10^8 \frac{m}{s}</math> )

===A Visual Model===

[[File:Spectrum.png|700 px]]

==Examples==

===Simple===
Calculate the frequency of violet light (450 nm).

1. <math>v = {\frac{c}{\lambda}}</math>

2. <math>450 \times 10^{-9} = \frac {2.998 \times 10^8}{\lambda}</math>

3. <math>\frac {1}{\lambda} = \frac {450 \times 10^{-9}}{2.998 \times 10^8} = 1.501 \times 10^{-15}</math>

4. <math>\lambda = 6.662 \times 10^{14}</math> Hz

===Difficult===
A small laser used as a pointer produces a beam of red light 2 mm in diameter, and has a power output of 4 milliwatts. What is the magnitude of the electric field in the laser beam?

1. <math>E = \sqrt {\frac{P/A}{c \times \epsilon_{0}}}</math>

2. <math>E = \sqrt { \frac{(4 \times 10^{-3}) / ((2/2) \pi \times 10^{-3 + -3})}{(2.998 \times 10^{8}) \times (8.85 \times 10^{-12})} }</math>

3. <math>E = \sqrt { \frac{4 \times 10^{3}}{2.65 \pi \times 10^{-3}} }</math>

4. <math>E = \sqrt {4.80 \times 10^5} = 6.93 \times 10^{2}</math>

==Interaction With Matter==

*Micro Waves - cause forces on molecules that cause torsion and rotation, causing friction in more strongly interconnected molecules, like food and other solids; this is why food heats up in a microwave oven
*Infrared Waves - causes molecular vibration, basically, this is what heat lamps produce, which is why the air gets hot around the lamp
*Visible Light - can produce ionization, but really acts more like infrared waves than ultraviolet waves
*Ultraviolet Waves - causes molecular ionization, but doesn't move the molecule around; this is why you get sunburned, because the ultraviolet light is destroying your skin

==History==

The first time that a part of the electromagnetic spectrum was observed was in 1800, when scientist William Herschel was looking at light from a heated object through a prism. He noticed that the light surpassed the color red, into what we now know today as the infrared frequency of light. Some years later in 1845, Micheal Faraday made the connection between light and electromagnetism, when he observed that polarized light responded to a magnet. James Maxwell made the final step, when he realized that electromagnetic waves must travel at the speed of light.

==Connectedness==
The electromagnetic spectrum is used for a variety of things including
*Cooking (microwaves)
*Radio and Communication
*Radar
*Military Defense
*Environmental Impacts (ultraviolet light)
*Medical Treatments (gamma rays, x-rays)
*Nuclear Physics
*The sense of sight

==References & Further Reading==

[[http://en.wikipedia.org/wiki/Electromagnetic_spectrum Electromagnetic Spectrum]][[http://www.school-for-champions.com/science/electromagnetic_spectrum.htm#.VmKF7TZllsM 2]]

[[http://en.wikipedia.org/wiki/Vacuum_permittivity Vacuum Permittivity]]

[[http://en.wikipedia.org/wiki/Electric_field Electric Field]]

[[http://revisionworld.com/gcse-revision/physics/waves/uses-electromagnetic-waves Uses of Electromagnetic Waves]]

[[Category:Waves]]

Electromagnetic Spectrum

2015-12-05T07:16:21Z

Croberts65:

This page has been created and claimed by Clayton Roberts (Croberts65)

The electromagnetic spectrum describes all different frequencies of light that can be observed, and is most commonly associated with the visible chromatic colors.

==The Main Idea==

The frequency in Hertz (Hz) of electromagnetic waves can be related to the energy and color (if applicable) of the type of electromagnetic radiation. This can be used in chemistry for ionization, among other fields of science where the material and relative temperature can be related.

===A Mathematical Model===

<math>v = {\frac{c}{\lambda}}</math>
where
*<math>v</math> is the frequency of the electromagnetic wave in Hertz (Hz) or number of cycles a second and can also be written as "<math>f</math>"
*<math>c</math> is the speed of light ( <math>2.998 \times 10^8 \frac{m}{s}</math> )
*<math>\lambda</math> is the wavelength in meters

<math>E = \sqrt {\frac{P/A}{c \times \epsilon_{0}}}</math>
where
*<math>E</math> is the magnitude of the electric field in Newtons per Columb (N/C)
*<math>P</math> is the power output of the beam of electromagnetic waves in Watts (W)
*<math>A</math> is the area of the beam in meters squared ( <math>m^{2}</math> )
*<math>\epsilon_{0}</math> is the vacuum permittivity constant ( <math>8.85 \times 10^{-12}</math> )
*<math>c</math> is the speed of light ( <math>2.998 \times 10^8 \frac{m}{s}</math> )

===A Visual Model===

[[File:Spectrum.png|700 px]]

==Examples==

===Simple===
Calculate the frequency of violet light (450 nm).

1. <math>v = {\frac{c}{\lambda}}</math>

2. <math>450 \times 10^{-9} = \frac {2.998 \times 10^8}{\lambda}</math>

3. <math>\frac {1}{\lambda} = \frac {450 \times 10^{-9}}{2.998 \times 10^8} = 1.501 \times 10^{-15}</math>

4. <math>\lambda = 6.662 \times 10^{14}</math> Hz

===Difficult===
A small laser used as a pointer produces a beam of red light 2 mm in diameter, and has a power output of 4 milliwatts. What is the magnitude of the electric field in the laser beam?

1. <math>E = \sqrt {\frac{P/A}{c \times \epsilon_{0}}}</math>

2. <math>E = \sqrt { \frac{(4 \times 10^{-3}) / ((2/2) \pi \times 10^{-3 + -3})}{(2.998 \times 10^{8}) \times (8.85 \times 10^{-12})} }</math>

3. <math>E = \sqrt { \frac{4 \times 10^{3}}{2.65 \pi \times 10^{-3}} }</math>

4. <math>E = \sqrt {4.80 \times 10^5} = 6.93 \times 10^{2}</math>

==Interaction With Matter==

*Micro Waves - cause forces on molecules that cause torsion and rotation, causing friction in more strongly interconnected molecules, like food and other solids; this is why food heats up in a microwave oven
*Infrared Waves - causes molecular vibration, basically, this is what heat lamps produce, which is why the air gets hot around the lamp
*Visible Light - can produce ionization, but really acts more like infrared waves than ultraviolet waves
*Ultraviolet Waves - causes molecular ionization, but doesn't move the molecule around; this is why you get sunburned, because the light is destroying your skin

==History==

The first time that a part of the electromagnetic spectrum was observed was in 1800, when scientist William Herschel was looking at light from a heated object through a prism. He noticed that the light surpassed the color red, into what we now know today as the infrared frequency of light. Some years later in 1845, Micheal Faraday made the connection between light and electromagnetism, when he observed that polarized light responded to a magnet. James Maxwell made the final step, when he realized that electromagnetic waves must travel at the speed of light.

==Connectedness==
The electromagnetic spectrum is used for a variety of things including
*Cooking (microwaves)
*Radio and Communication
*Radar
*Military Defense
*Environmental Impacts (ultraviolet light)
*Medical Treatments (gamma rays, x-rays)
*Nuclear Physics
*The sense of sight

==References & Further Reading==

[[http://en.wikipedia.org/wiki/Electromagnetic_spectrum Electromagnetic Spectrum]][[http://www.school-for-champions.com/science/electromagnetic_spectrum.htm#.VmKF7TZllsM 2]]

[[http://en.wikipedia.org/wiki/Vacuum_permittivity Vacuum Permittivity]]

[[http://en.wikipedia.org/wiki/Electric_field Electric Field]]

[[http://revisionworld.com/gcse-revision/physics/waves/uses-electromagnetic-waves Uses of Electromagnetic Waves]]

[[Category:Waves]]

Electromagnetic Spectrum

2015-12-05T07:06:20Z

Croberts65:

This page has been created and claimed by Clayton Roberts (Croberts65)

The electromagnetic spectrum describes all different frequencies of light that can be observed, and is most commonly associated with the visible chromatic colors.

==The Main Idea==

The frequency in Hertz (Hz) of electromagnetic waves can be related to the energy and color (if applicable) of the type of electromagnetic radiation. This can be used in chemistry for ionization, among other fields of science where the material and relative temperature can be related.

===A Mathematical Model===

<math>v = {\frac{c}{\lambda}}</math>
where
*<math>v</math> is the frequency of the electromagnetic wave in Hertz (Hz) or number of cycles a second and can also be written as "<math>f</math>"
*<math>c</math> is the speed of light ( <math>2.998 \times 10^8 \frac{m}{s}</math> )
*<math>\lambda</math> is the wavelength in meters

<math>E = \sqrt {\frac{P/A}{c \times \epsilon_{0}}}</math>
where
*<math>E</math> is the magnitude of the electric field in Newtons per Columb (N/C)
*<math>P</math> is the power output of the beam of electromagnetic waves in Watts (W)
*<math>A</math> is the area of the beam in meters squared ( <math>m^{2}</math> )
*<math>\epsilon_{0}</math> is the vacuum permittivity constant ( <math>8.85 \times 10^{-12}</math> )
*<math>c</math> is the speed of light ( <math>2.998 \times 10^8 \frac{m}{s}</math> )

===A Visual Model===

[[File:Spectrum.png|700 px]]

==Examples==

===Simple===
Calculate the frequency of violet light (450 nm).

1. <math>v = {\frac{c}{\lambda}}</math>

2. <math>450 \times 10^{-9} = \frac {2.998 \times 10^8}{\lambda}</math>

3. <math>\frac {1}{\lambda} = \frac {450 \times 10^{-9}}{2.998 \times 10^8} = 1.501 \times 10^{-15}</math>

4. <math>\lambda = 6.662 \times 10^{14}</math> Hz

===Difficult===
A small laser used as a pointer produces a beam of red light 2 mm in diameter, and has a power output of 4 milliwatts. What is the magnitude of the electric field in the laser beam?

1. <math>E = \sqrt {\frac{P/A}{c \times \epsilon_{0}}}</math>

2. <math>E = \sqrt { \frac{(4 \times 10^{-3}) / ((2/2) \pi \times 10^{-3 + -3})}{(2.998 \times 10^{8}) \times (8.85 \times 10^{-12})} }</math>

3. <math>E = \sqrt { \frac{4 \times 10^{3}}{2.65 \pi \times 10^{-3}} }</math>

4. <math>E = \sqrt {4.80 \times 10^5} = 6.93 \times 10^{2}</math>

==Interaction With Matter==

{|class="wikitable" style="margin: 1em auto 1em auto; width:70%; font-size:95%;
|+Electromagnetic radiation interaction with matter
|- style="text-align:center; background:#BBB;"
|-
! Region of the spectrum
! Main interactions with matter
|-
|[[Radio wave|Radio]]
|Collective oscillation of charge carriers in bulk material ([[plasma oscillation]]). An example would be the oscillatory travels of the electrons in an [[antenna (radio)|antenna]].
|-
|nowrap|[[Microwave]] through far [[infrared]]
|Plasma oscillation, molecular rotation
|-
|Near [[infrared]]
|Molecular vibration, plasma oscillation (in metals only)
|-
|[[Light|Visible]]
|Molecular electron excitation (including pigment molecules found in the human retina), plasma oscillations (in metals only)
|-
|[[Ultraviolet]]
|Excitation of molecular and atomic valence electrons, including ejection of the electrons ([[photoelectric effect]])
|-
|[[Xray|X-rays]]
|Excitation and ejection of core atomic electrons, [[Compton scattering]] (for low atomic numbers)
|-
|[[Gamma ray]]s
|Energetic ejection of core electrons in heavy elements, [[Compton scattering]] (for all atomic numbers), excitation of atomic nuclei, including dissociation of nuclei
|-
|nowrap|High-energy [[gamma ray]]s
|Creation of [[Virtual pair|particle-antiparticle pairs]]. At very high energies a single photon can create a shower of high-energy particles and antiparticles upon interaction with matter.
|}

==History==

The first time that a part of the electromagnetic spectrum was observed was in 1800, when scientist William Herschel was looking at light from a heated object through a prism. He noticed that the light surpassed the color red, into what we now know today as the infrared frequency of light. Some years later in 1845, Micheal Faraday made the connection between light and electromagnetism, when he observed that polarized light responded to a magnet. James Maxwell made the final step, when he realized that electromagnetic waves must travel at the speed of light.

==Connectedness==
The electromagnetic spectrum is used for a variety of things including
*Cooking (microwaves)
*Radio and Communication
*Radar
*Military Defense
*Environmental Impacts (ultraviolet light)
*Medical Treatments (gamma rays, x-rays)
*Nuclear Physics
*The sense of sight

==References & Further Reading==

[[http://en.wikipedia.org/wiki/Electromagnetic_spectrum Electromagnetic Spectrum]][[http://www.school-for-champions.com/science/electromagnetic_spectrum.htm#.VmKF7TZllsM 2]]

[[http://en.wikipedia.org/wiki/Vacuum_permittivity Vacuum Permittivity]]

[[http://en.wikipedia.org/wiki/Electric_field Electric Field]]

[[http://revisionworld.com/gcse-revision/physics/waves/uses-electromagnetic-waves Uses of Electromagnetic Waves]]

[[Category:Waves]]

Electromagnetic Spectrum

2015-12-05T06:58:40Z

Croberts65:

This page has been created and claimed by Clayton Roberts (Croberts65)

The electromagnetic spectrum describes all different frequencies of light that can be observed, and is most commonly associated with the visible chromatic colors.

==The Main Idea==

The frequency in Hertz (Hz) of electromagnetic waves can be related to the energy and color (if applicable) of the type of electromagnetic radiation. This can be used in chemistry for ionization, among other fields of science where the material and relative temperature can be related.

===A Mathematical Model===

<math>v = {\frac{c}{\lambda}}</math>
where
*<math>v</math> is the frequency of the electromagnetic wave in Hertz (Hz) or number of cycles a second and can also be written as "<math>f</math>"
*<math>c</math> is the speed of light ( <math>2.998 \times 10^8 \frac{m}{s}</math> )
*<math>\lambda</math> is the wavelength in meters

<math>E = \sqrt {\frac{P/A}{c \times \epsilon_{0}}}</math>
where
*<math>E</math> is the magnitude of the electric field in Newtons per Columb (N/C)
*<math>P</math> is the power output of the beam of electromagnetic waves in Watts (W)
*<math>A</math> is the area of the beam in meters squared ( <math>m^{2}</math> )
*<math>\epsilon_{0}</math> is the vacuum permittivity constant ( <math>8.85 \times 10^{-12}</math> )
*<math>c</math> is the speed of light ( <math>2.998 \times 10^8 \frac{m}{s}</math> )

===A Visual Model===

[[File:Spectrum.png|700 px]]

==Examples==

Be sure to show all steps in your solution and include diagrams whenever possible

===Simple===
Calculate the frequency of violet light (450 nm).

1. <math>450 \times 10^{-9} = \frac {2.998 \times 10^8}{\lambda}</math>

2. <math>\frac {1}{\lambda} = \frac {450 \times 10^{-9}}{2.998 \times 10^8} = 1.501 \times 10^{-15}</math>

3. <math>\lambda = 6.662 \times 10^{14}</math> Hz

===Difficult===
A small laser used as a pointer produces a beam of red light 2 mm in diameter, and has a power output of 4 milliwatts. What is the magnitude of the electric field in the laser beam?

1. <math>E = \sqrt { \frac{(4 \times 10^{-3}) / ((2/2) \pi \times 10^{-3 + -3})}{(2.998 \times 10^{8}) \times (8.85 \times 10^{-12})} }</math>

2. <math>E = \sqrt { \frac{4 \times 10^{3}}{2.65 \pi \times 10^{-3}} }</math>

3. <math>E = \sqrt {4.80 \times 10^5} = 6.93 \times 10^{2}</math>

==History==

The first time that a part of the electromagnetic spectrum was observed was in 1800, when scientist William Herschel was looking at light from a heated object through a prism. He noticed that the light surpassed the color red, into what we now know today as the infrared frequency of light. Some years later in 1845, Micheal Faraday made the connection between light and electromagnetism, when he observed that polarized light responded to a magnet. James Maxwell made the final step, when he realized that electromagnetic waves must travel at the speed of light.

==Connectedness==
We can use this for a variety of things including
*Cooking (microwaves)
*Radio and Communication
*Radar
*Military Defense
*Environmental Impacts (ultraviolet light)
*Medical Treatments (gamma rays, x-rays)
*Nuclear Physics

==References & Further Reading==

[[http://en.wikipedia.org/wiki/Electromagnetic_spectrum Electromagnetic Spectrum]][[http://www.school-for-champions.com/science/electromagnetic_spectrum.htm#.VmKF7TZllsM 2]]

[[http://en.wikipedia.org/wiki/Vacuum_permittivity Vacuum Permittivity]]

[[http://en.wikipedia.org/wiki/Electric_field Electric Field]]

[[http://revisionworld.com/gcse-revision/physics/waves/uses-electromagnetic-waves Uses of Electromagnetic Waves]]

[[Category:Waves]]

Electromagnetic Spectrum

2015-12-05T06:58:24Z

Croberts65:

This page has been created and claimed by Clayton Roberts (Croberts65)

The electromagnetic spectrum describes all different frequencies of light that can be observed, and is most commonly associated with the visible chromatic colors.

==The Main Idea==

The frequency in Hertz (Hz) of electromagnetic waves can be related to the energy and color (if applicable) of the type of electromagnetic radiation. This can be used in chemistry for ionization, among other fields of science where the material and relative temperature can be related.

===A Mathematical Model===

<math>v = {\frac{c}{\lambda}}</math>
where
*<math>v</math> is the frequency of the electromagnetic wave in Hertz (Hz) or number of cycles a second and can also be written as "<math>f</math>"
*<math>c</math> is the speed of light ( <math>2.998 \times 10^8 \frac{m}{s}</math> )
*<math>\lambda</math> is the wavelength in meters

<math>E = \sqrt {\frac{P/A}{c \times \epsilon_{0}}}</math>
where
*<math>E</math> is the magnitude of the electric field in Newtons per Columb (N/C)
*<math>P</math> is the power output of the beam of electromagnetic waves in Watts (W)
*<math>A</math> is the area of the beam in meters squared ( <math>m^{2}</math> )
*<math>\epsilon_{0}</math> is the vacuum permittivity constant ( <math>8.85 \times 10^{-12}</math> )
*<math>c</math> is the speed of light ( <math>2.998 \times 10^8 \frac{m}{s}</math> )

===A Visual Model===

[[File:Spectrum.png|700 px]]

==Examples==

Be sure to show all steps in your solution and include diagrams whenever possible

===Simple===
Calculate the frequency of violet light (450 nm).

1. <math>450 \times 10^{-9} = \frac {2.998 \times 10^8}{\lambda}</math>

2. <math>\frac {1}{\lambda} = \frac {450 \times 10^{-9}}{2.998 \times 10^8} = 1.501 \times 10^{-15}</math>

3. <math>\lambda = 6.662 \times 10^{14}</math> Hz

===Difficult===
A small laser used as a pointer produces a beam of red light 2 mm in diameter, and has a power output of 4 milliwatts. What is the magnitude of the electric field in the laser beam?

1. <math>E = \sqrt { \frac{(4 \times 10^{-3}) / ((2/2) \pi \times 10^{-3 + -3})}{(2.998 \times 10^{8}) \times (8.85 \times 10^{-12})} }</math>

2. <math>E = \sqrt { \frac{4 \times 10^{3}}{2.65 \pi \times 10^{-3}} }</math>

3. <math>E = \sqrt {4.80 \times 10^5} = 6.93 \times 10^{2}

==History==

The first time that a part of the electromagnetic spectrum was observed was in 1800, when scientist William Herschel was looking at light from a heated object through a prism. He noticed that the light surpassed the color red, into what we now know today as the infrared frequency of light. Some years later in 1845, Micheal Faraday made the connection between light and electromagnetism, when he observed that polarized light responded to a magnet. James Maxwell made the final step, when he realized that electromagnetic waves must travel at the speed of light.

==Connectedness==
We can use this for a variety of things including
*Cooking (microwaves)
*Radio and Communication
*Radar
*Military Defense
*Environmental Impacts (ultraviolet light)
*Medical Treatments (gamma rays, x-rays)
*Nuclear Physics

==References & Further Reading==

[[http://en.wikipedia.org/wiki/Electromagnetic_spectrum Electromagnetic Spectrum]][[http://www.school-for-champions.com/science/electromagnetic_spectrum.htm#.VmKF7TZllsM 2]]

[[http://en.wikipedia.org/wiki/Vacuum_permittivity Vacuum Permittivity]]

[[http://en.wikipedia.org/wiki/Electric_field Electric Field]]

[[http://revisionworld.com/gcse-revision/physics/waves/uses-electromagnetic-waves Uses of Electromagnetic Waves]]

[[Category:Waves]]

Electromagnetic Spectrum

2015-12-05T06:55:48Z

Croberts65:

Electromagnetic Spectrum

2015-12-05T06:52:58Z

Croberts65:

Electromagnetic Spectrum

2015-12-05T06:52:31Z

Croberts65:

Electromagnetic Spectrum

2015-12-05T06:50:58Z

Croberts65:

Electromagnetic Spectrum

2015-12-05T06:50:31Z

Croberts65:

Electromagnetic Spectrum

2015-12-05T06:49:39Z

Croberts65:

Electromagnetic Spectrum

2015-12-05T06:48:51Z

Croberts65:

Electromagnetic Spectrum

2015-12-05T06:48:29Z

Croberts65:

Electromagnetic Spectrum

2015-12-05T06:39:41Z

Croberts65:

Electromagnetic Spectrum

2015-12-05T06:38:31Z

Croberts65:

Electromagnetic Spectrum

2015-12-05T06:38:17Z

Croberts65:

Electromagnetic Spectrum

2015-12-05T06:35:42Z

Croberts65:

Electromagnetic Spectrum

2015-12-04T05:23:37Z

Croberts65:

Electromagnetic Spectrum

2015-12-04T05:23:12Z

Croberts65:

Electromagnetic Spectrum

2015-12-04T05:21:56Z

Croberts65:

Electromagnetic Spectrum

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