Components

This page covers basic electronic components such as resistors, capacitors, and batteries.

claimed by Bradleyarg

The Main Idea

There are 5 basic components need for the class:

Batteries:

An electric battery is a device consisting of two or more electrochemical cells that convert stored chemical energy into electrical energy. Each cell has a positive terminal, or cathode, and a negative terminal, or anode. The terminal marked positive is at a higher electrical potential energy than is the terminal marked negative. The terminal marked positive is the source of electrons that when connected to an external circuit will flow and deliver energy to an external device. When a battery is connected to an external circuit, electrolytes are able to move as ions within, allowing the chemical reactions to be completed at the separate terminals and so deliver energy to the external circuit. It is the movement of those ions within the battery which allows current to flow out of the battery to perform work.

Each half-cell has an electromotive force (or emf), determined by its ability to drive electric current from the interior to the exterior of the cell. The net emf of the cell is the difference between the emfs of its half-cells. Thus, if the electrodes have emfs [math]\displaystyle{ \mathcal{E}_1 }[/math] and [math]\displaystyle{ \mathcal{E}_2 }[/math], then the net emf is [math]\displaystyle{ \mathcal{E}_{2}-\mathcal{E}_{1} }[/math]; in other words, the net emf is the difference between the reduction potentials of the half-reactions.

The electrical driving force or ΔV across the terminals of a cell is known as the terminal voltage (difference) and is measured in volts. The terminal voltage of a cell that is neither charging nor discharging is called the open-circuit voltage and equals the emf of the cell. Because of internal resistance, the terminal voltage of a cell that is discharging is smaller in magnitude than the open-circuit voltage and the terminal voltage of a cell that is charging exceeds the open-circuit voltage.

Resistors:

A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. Resistors act to reduce current flow, and, at the same time, act to lower voltage levels within circuits.

Capacitors:

A capacitor is a passive two-terminal electrical component used to store electrical energy temporarily in an electric field. Capacitors contain at least two electrical conductors (plates) separated by a dielectric (i.e. an insulator that can store energy by becoming polarized). The nonconducting dielectric acts to increase the capacitor's charge capacity. A dielectric can be glass, ceramic, plastic film, air, vacuum, paper, mica, oxide layer etc. Capacitors are widely used as parts of electrical circuits in many common electrical devices. Unlike a resistor, an ideal capacitor does not dissipate energy. Instead, a capacitor stores energy in the form of an electrostatic field between its plates.

When there is a potential difference across the conductors (e.g., when a capacitor is attached across a battery), an electric field develops across the dielectric, causing positive charge +Q to collect on one plate and negative charge −Q to collect on the other plate. If a battery has been attached to a capacitor for a sufficient amount of time, no current can flow through the capacitor. However, if a time-varying voltage is applied across the leads of the capacitor, a displacement current can flow.

An ideal capacitor is characterized by a single constant value, its capacitance. Capacitance is defined as the ratio of the electric charge Q on each conductor to the potential difference V between them. The SI unit of capacitance is the farad (F), which is equal to one coulomb per volt (1 C/V). Typical capacitance values range from about 1 pF (10−12 F) to about 1 mF (10−3 F).

Switches:

In electrical engineering, a switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another. The mechanism of a switch may be operated directly by a human operator to control a circuit (for example, a light switch or a keyboard button), may be operated by a moving object such as a door-operated switch, or may be operated by some sensing element for pressure, temperature or flow. A relay is a switch that is operated by electricity. Switches are made to handle a wide range of voltages and currents; very large switches may be used to isolate high-voltage circuits in electrical substations.

Node:

A node is a point of intersection in a circuit where the circuitry splits into 2 or more paths. A node is important in the distribution of charge and the effect it has on voltage and amperage.

Examples

A Circuit Model

Batteries:

Resistors:

Capacitors:

Switch:

Node:

Connectedness

1. How is this topic connected to something that you are interested in?
   1. The components of a circuit determine various characteristics of the circuit. Circuitry models is a the universal way of conveying information about the layout and setup of a circuit.
2. How is it connected to your major?
   1. Mechanical Engineering: Components of a circuit are important in that they are typically necessary parts to be understood in the designing of a device. Also, these devices are often necessary to be utilized inorder to collect data for expiremental research (for example: acoustical research into design. ) into various fields of mechanical engineering.
3. Is there an interesting industrial application?
   1. Components of a circuit is in itself interesting, but specifically these are the base behind how any electrical device works. How electricity is manipulated, and how many of our modern day conveniences are operated.

History

Battery:

Put this idea in historical context. Give the reader the Who, What, When, Where, and Why. The usage of "battery" to describe a group of electrical devices dates to Benjamin Franklin, who in 1748 described multiple Leyden jars by analogy to a battery of cannon (Benjamin Franklin borrowed the term "battery" from the military, which refers to weapons functioning together).

Alessandro Volta built and described the first electrochemical battery, the voltaic pile, in 1800. This was a stack of copper and zinc plates, separated by brine-soaked paper disks, that could produce a steady current for a considerable length of time. Volta did not appreciate that the voltage was due to chemical reactions. He thought that his cells were an inexhaustible source of energy,[6] and that the associated corrosion effects at the electrodes were a mere nuisance, rather than an unavoidable consequence of their operation, as Michael Faraday showed in 1834.

Resistor:

The Resistance was discovered by the year 1827 from Georg Simon Ohm, a German electrician. Ohm was born in Germany, in the city of Erlangen at 1787 and died at 1854.

Georg Simon Ohm noticed that different materials that are considered as electrically conductive, will not allow the current to flow within their body with the same ease. The difficulty that each material had, had to do with some parameters such as the type of the material and some external factors such as the temperature or the humidity of the atmosphere.

G.S.Ohm described this behavior and gave the name "Resistance".

Capacitor:

"The invention of the capacitor varies somewhat depending on who you ask. There are records that indicate a German scientist named Ewald Georg von Kleist invented the capacitor in November 1745. Several months later Pieter van Musschenbroek, a Dutch professor at the University of Leyden came up with a very similar device in the form of the Leyden jar, which is typically credited as the first capacitor. Since Kleist didn't have detailed records and notes, nor the notoriety of his Dutch counterpart, he's often overlooked as a contributor to the capacitor's evolution. However, over the years, both have been given equal credit as it was established that their research was independent of each other and merely a scientific coincidence." Source: http://electronics.howstuffworks.com/capacitor3.htm

See also

Are there related topics or categories in this wiki resource for the curious reader to explore? How does this topic fit into that context?

External links

Internet resources on this topic

References

http://www.physicsclassroom.com/mmedia/momentum/cthoe.cfm

Further reading

• Dingrando, Laurel; et al. (2007). Chemistry: Matter and Change. New York: Glencoe/McGraw-Hill. ISBN 978-0-07-877237-5. Ch. 21 (pp. 662–695) is on electrochemistry.
• Fink, Donald G.; H. Wayne Beaty (1978). Standard Handbook for Electrical Engineers, Eleventh Edition. New York: McGraw-Hill. ISBN 0-07-020974-X.
• Knight, Randall D. (2004). Physics for Scientists and Engineers: A Strategic Approach. San Francisco: Pearson Education. ISBN 0-8053-8960-1. Chs. 28–31 (pp. 879–995) contain information on electric potential.
• Linden, David; Thomas B. Reddy (2001). Handbook of Batteries. New York: McGraw-Hill. ISBN 0-07-135978-8.
• Saslow, Wayne M. (2002). Electricity, Magnetism, and Light. Toronto: Thomson Learning. ISBN 0-12-619455-6. Chs. 8–9 (pp. 336–418) have more information on batteries.