Energy conservation law violated(seems to be)!

sazmat
the charge(say positive) in figure induces negative charge on the disc and positive on sphere, the net force on charge is attractive towards the disc and is a function of position, now if someone moves the charge the amount of charge on disc changes accordingly and force changes its magnitude but remains attractive, if same person vibrates the charge on the line shown the net work done during one vibration is zero, but energy has been dissipated in form of heat due to the current that flowed in wire as the charge on disc changes magnitude, where did that energy came from as external work done is zero?