Each plate of a parallel -plate air capacitor has an area `S`. What amount of work has to be performed to slowly increases teh distance between the plates from `x_(1)` to `x_(2)` if
(a) Capacitance of the capacitor which is equal to `q`, or (b) the voltage across the capacitor, which is equal to `V`, is kept constant in the process?

Options

A. ` ( q^(2) (x_2 +x_1))/( 2e_0 S ) `
B. ` ( q^(2) (x_2 - x_1))/( 2e_0 S ) `
C. ` ( q^(2) (x_2 - x_1))/( e_0 S ) `
D. ` ( q^(2) (x_1 - x_2))/( 2e_0 S ) `

Answer

B