A parallel plate air capacitor has plate area A and separation between the plates d. Switch S is closed to connect the capacitors to a cell of emf V.
(a) Calculate the amount of heat generated in the circuit as the capacitor gets charged.
(b) Calculate the force (F) that one capacitor plate exerts on the other. (c) The distance between the plates is slowly reduced to `(d)/(2)`. Calculate the work done by the external agent in the process. For your calculation use the basic definition of work as work = force `xx` displacement.
(d) How much energy is dissipated in the circuit as the distance between the plates is reduced from d to `(d)/(2)` ? Try to give answer without any calculations. Give reasons. Now use work energy theorem to show that your answer is right.

Answer

(a) `(1)/(2)CV^(2)`
(b) `(in_(0)AV^(2))/(2d^(2))`
(c) `-(1)/(2)CV^(2)`
(d) zero