Capacitor—

A capacitor is a system of two conductors that is used to store electric charge as well as electrical energy.

Principle of a Capacitor—

Let us consider two metal plates. If +Q charge is given to one plate, this charge will spread over it. Due to induction the closer surface of second plate acquires opposite charge and other surface get same charge. Now, if second surface is earthed its charge gets neutralized. Now both plates will be oppositely charged. Because of opposite charge both charges will hold each other and it reduces the potential of first plate also which increases the capacitance. Such system of two conductors is called Capacitor.

Capacitor is represented by the symbols---