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Solution
CAPACITORS:
- Apart from resistors and insulators, a capacitor is also the other basic passive component commonly used in electrical circuits. Capacitor is a device which has the ability to store charges in the form of electrical energy, which neither a resistor nor an insulator can do.
- An ideal capacitor may retain the charges stored in it for a long time, after power supply is removed from the circuit. That is, it can store charges for ever. This stored charge can discharge through a conductor (or) wire. This discharge can cause shock or damage to the connected equipment, during the misuse of capacitors in a circuit.
Construction of a capacitor :
- Two similar metallic conductors separated by an insulator (or) dielectric medium forms a capacitor. Conductor – insulator – conductor sequence is the basic idea behind a capacitor.
The basic difference between insulator and dielectric medium is :
The materials which do not have free electrons in them are unable to conduct electricity and they are termed as insulators.
Some material like ceramic behaves as a dielectric medium. Charges are induced in the opposite faces of it, because of the external applied electric field. Such material is called dielectric.
All dielectric materials are insulators, but not all insulators make good dielectric materials.
The dielectric medium could be air, mica, ceramic, paper, polyester, Teflon, etc.
In the figure shown below two metallic conductors of equal area “A” separated by a dielectric medium, forms a two terminal device, named as Capacitor.
- The plates are kept perfectly parallel to each other. So it is called as parallel plate capacitor. The conducting plates of a capacitor can be either square or circular or rectangular or cylindrical or spherical in shape. Shape selection depends on its application and voltage rating.