The Physics of a Capacitor

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Today in modern life, humans make use of many objects that have certain devices that they are not even aware of how they work or what their main function is. One of these devices that is used a lot without knowing their existence is what is called a "capacitor." Many people have heard the word capacitor, but also many do not even have an idea of what it means or what is the use for it. In this research, I will concentrate on explaining the physics of a capacitor and describing the main types of capacitors that exist today.

A capacitor is a device used to store charge in an electrical circuit. The function of a capacitor is much similar to a battery, but it charges and discharges much more efficiently. Also, unlike a battery, a capacitor does not produce electrons; it only stores them.

A basic capacitor is made up of two conductors on which equal but opposite electric charges are placed, and an insulator, which is also called a dielectric, separates the two conductors. This dielectric could be made of paper, plastic, mica, ceramic, glass, or almost any other nonconductive material. Because each conductor stores an equal but opposite charge, the total charge in the device is always zero.

The electron storing ability of a capacitor is called "capacitance" (C), and it is measured in Farads. The capacitance (C) is a measure of the amount of charge (Q) stored on each conductor (plate) for a given potential difference or voltage (V). The formula that represents this relation is C = Q/V. In SI units, a capacitor's capacitance is one Farad, which means one coulomb per volt.

Since the Farad is a very large unit, capacitors are usually rated in microfarads (mF=106F), nanofarads (nF=10-9F), and picofarads (pF=10-12F).

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...cs. Last of all, electric double layer capacitors have extreme high capacitances of hundreds or even thousands of farads. These capacitors use a molecule-thin layer of electrolyte as the dielectric, thus having an extremely high energy density.

As time and technology have advanced, better and more efficient capacitors have been built. In present time, different companies are performing studies on trying to use Niobium as a new type of dielectric. If this substance were to be used, it would be possible to create very small capacitors with very large capacities. Definitely, the search for improved capacitors and better technology would not have a definite stop.

Works Cited

Dummer, G. W. A. Fixed Capacitors: Radio and Electronic Components. Vol. 3. 1996.

Van Roon, Tony "What Exactly Is A Capacitor?" 2001

http://www.uoguelph.ca/~antoon/gadgets/caps/caps.html

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