A parallel plate capacitor having capacitance 12pF is charged bya battery to a potential difference of 10V between its plates. The charging battery is now disonnected and a porcelain slab of dielectric constant 6.5 is slipped between the plates. The work done by the capacitor on the slab is

Options

A. 560pJ
B. 692pJ
C. 508pJ
D. 600pJ

Answer

C

Explanation

`DeltaU=Q^(2)[(1)/(2kc)-(1)/(2c)]=(5.5xxc^(2)E^(2))/(6.5xx2c)=-508xx10^(-12)J,W=-DeltaU=508xx10^(-12)J=508pJ`