Question

Prove that energy stored per unit volume in a capacitor is given by 1/2€0 E2 , where
E is the electric field of the capacitor?​

Answer 1

Answer:

Energy stored in a capacitor is given by:

E=21CV2

Using C=dεoA 

E=21εoAdd2V2

Using potential gradient, E=dV

AdE=21εoE2

The term on the left hand side is the energy stored per unit volume in a capacitor.

(b)

As electric field is conservative, net work done by electric force in moving a charge through a loop is zero.