Two small metal spheres having equal charge and mass are suspended from some point on the ceiling of a damp room with silk threads of equal length. Let centre to centre distance between sphere be x, x << l, l is length of silk thread. Due to ionization of medium, charge leaks off from each sphere and they keep on coming closer to each other at a constant rate.Let their approach velocity y varies as v∝x−1/2If mass of each sphere is m then the rate at which charge varies with respect to time is dqdt∝N22πε0mgl. The value of N is _________.