A ring of radius R having a uniformly distributed charge is fixed in a horizontal plane. A bead of mass m and an unknown charge stays in equilibrium at such point on the vertical axis of the ring that if it is displaced slightly up or down, it undergoes oscillatory motion. Find charge on the bead. Intensity of gravitational field is g. Bead R

A ring of radius R having a uniformly distributed charge is fixed in a horizontal plane. A bead of mass m and an unknown charge stays in equilibrium at such point on the vertical axis of the ring that if it is displaced slightly up or down, it undergoes oscillatory motion. Find charge on the bead. Intensity of gravitational field is g. Bead R