A parallel plate condenser with a dielectric of dielectric constant K between the plates has a capacity C and is charged to a potential V volt. The dielectric slab is slowly removed from between the plates and then reinserted. The net work done by the system in this process is

Options

A. `(1)/(2)(K-1) CV^(2)`
B. `CV^(2)(K-1)//K`
C. `(K-1)CV^(2)`
D. zero

Answer

D

Explanation

On introduction and removal and again on introduction, the capacity and potential remain same. So, net work done by the system in this process
`Q=U_(f)-U_(i),(1)/(2) CV^(2)-(1)/(2)CV^(2)=0`.