Two small equal point charges of magnitude q are suspended from a common point on the ceiling by insulating mass less strings of equal lengths. They come to equilibrium with each string making angle θ from the vertical. If the mass of each charge is m, then the electrostatic potential at the centre of line joining them will be (4πϵ01=k) .
a. 2kmgtanθ
b. kmgtanθ
c. 4kmg/tanθ
d. kmg/tanθ