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

Answer

B

Explanation

In this case, there is no change in the initial and final electrostatic energy stored in the condenser i.e. `U_(1)=U_(2)`.
`therefore`Net work done by the system `=U_(2)-U_(1)=0`