A conducting sphere of radius R carrying charge Q lies inside an uncharged conducting shell of radius 2R. If they are joined by a metal wire, the amount of heat that will be produced is:

When connected by metal wire, whole of the charge would be transferred to the outer conducting shell. Capacitance of the two system are Ci = 4πε₀(R) and Cf = 4πε₀(2R) Thus initial energy = Q²/2Ci Final energy = Q²/2Cf The energy amount of heat produced is equal to the change in potential energy of the system = Q²/2Ci − Q²/2Cf = 14πε₀.Q²/4R