A parallel plate capacitor of capacitance `C_(0)` is charged using a cell of emf `V_(0)`. Calculate the work done in reduc- ing the separation between the plates to half its original value if
(a) The cell is disconnected before you start decreasing the plate separation
(b) The cell remains connected while you are reducing the separation
Assume that the plates are moved very slowly.

Answer

(a) `-(1)/(4)C_(0)V_(0)^(2)`
(b) `-(1)/(2)C_(0)V_(0)^(2)`