Showing posts with label R-C network. Show all posts
Showing posts with label R-C network. Show all posts

Friday, 8 February 2013

Capacitor

CAPACITOR

What is a Capacitor?

A capacitor is a device for storing electrical charges. It consists of two conductors or metal plates separated by an insulating material known as the dielectric. These plates are parallel to each other. The charge stored in a capacitor is proportional to an increase in its conductivity.
When one of the plates is charged with electricity from a direct-current or electrostatic source, the other plate of the capacitor will have an induced charge of the opposite sign. That is to say, if the charge at one of the plate is positive, the other plate will have a negative charge. The amount of electric charge a capacitor can hold is known as its “capacitance”.

When a source of power is connected across both plates, there will be an electric current flow for a short time and accumulate on each plate.

A capacitor is denoted with the symbol C, with the measure of capacitance measured in “Farad”. The capacitance of a capacitor is defined as the ratio of electric charge to the potential difference (voltage) between or across the plates of the capacitor. Therefore the charge in any plate is directly proportional to the potential difference across the capacitor. This is expressed mathematically as:

Q α V
Q = CV where C = constant called capacitance
C = Q/V. for the sake of this blog been basic, I will stop here so as not to make it complex.


Below shows the symbol and diagram of a capacity:

TYPES OF CAPACITOR AND BASIC APPLICATIONS

There are basically three (4) types of capacitor namely: Ceramics capacitor, Variable air capacitor, Paper capacitor and Mica capacitor. And vacuums (open space) are use as “di-electric” pending on the intention or design for which such capacitor is meant to do. Some capacitor uses Glass, Mica, Porcelain and mineral oils as their di-electric.

A good di-electric must have the ability to return some percentage of the electric charge stored in it when the field is alternated or reversed. The parts or fractions of charge lost are known as the power factor of the di-electric:

Generally, capacitors have limits to the level or amount of charge they can hold. They can conduct direct-current for just once but they work well as conductors in a.c circuits (alternating current). This unique property makes them useful when we want to block the passage of direct-current (D.C) from entering some part of a circuit or stage in a circuit design.

Variable capacitors and fixed capacitors are occasionally use in circuits alongside with inductors (coils) as resonant circuits in radio and other electronics circuitry (electronics equipment).

Larger capacitors are also use in Power Lines to resonate the load on that line as to make it possible to generate more power.

Thanks for keeping it date again. next, i will show you how to identify and know values of capacitors. ok!

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