AIPMT 2008 Physics and Chemistry Paper

Energy stored in capacitor for field
E=‌

1

2

CV2
=‌

1

2

(‌

ε0A

d

)(E⋅d)2
=‌

1

2

ε0AE2d
Energy stored in capacitor + Energy loss in the process of charging = Energy given by cell.
=(‌

Aε0

d

)V2
=2× Energy stored in capacitor
Since energy stored in capacitor = Energy loss in the process of storing the charge in capacitor.