AAI ATC Junior Executive 25 Mar 2021 Shift 2 Paper

A very small sphere of mass 60 g having a charge q is held at a height of 7m vertically above the center of a fixed conducting sphere of radius 1 m, carrying an equal charge q. When released, it falls until it is repelled back just before it comes in contact with the sphere as shown in given figure. Find the charge? (g = 10 m/s²)