Q.

A parallel plate capacitor has a uniform electric field 'E' in the space between the plates. If the distance between the plates is 'd' and the area of each plate 'A', the energy stored in the capacitor is (ε0 = permittivity of free space)             [2021]

1 E2Adε0  
2 12ε0E2  
3 ε0EAd  
4 12ε0E2Ad  

Ans.

(4)

The capacitance of a parallel plate capacitor of plate area A and separation d is given by

              C=ε0Ad

The potential is given by V=Ed

Where E is electric field.

Energy, U=12CV2=12×ε0Ad×E2d2  ;  U=12ε0E2Ad