Capacitor and its Principle

Table of Contents

Capacitor and its Principle:

What is Capacitor?

It is an arrangement used for storing large amounts of electric charge and hence electric energy.

An arrangement of two conductors separated by a dielectric medium is said to form a capacitor or condenser. It is of three types-

If the conductors are plane, the capacitor is called parallel plate capacitor.
If the conductors are spherical, the capacitor is called spherical capacitor.
If the conductors are cylindrical, it is called cylindrical capacitor.

Principle of Capacitor:

Let us take a plate X. Give some charge to plate X, till its potential becomes maximum. Now consider another plate Y, held near plate X. Due to the phenomenon of induction, a negative charge is induced on the inner side of plate Y and an equal positive charge is induced on the outer side of plate Y. As the negative charge on the plate Y is nearer to plate X, hence it is more effective. The negative charge on plate Y will reduce the positive charge on plate X. Hence the potential of plate X decreases. In other words, the capacity of plate X increases. Now connect the plate Y to earth, all the positive charges on plate Y will go to earth. Now the negative charge on plate Y will further reduce the positive charge on plate X. Hence the potential of plate X further decreases. In other words, the capacity of plate X increases.

Thus, when we bring an uncharged earth-connected rod near a charged rod, the capacity of charged rod increases.