A fixed ring of radius R is placed horizontally.It carries uniform charge distribution on its circumference . A piont mass m is in equlibrium at y height above centre of ring . For small disturbance along y axis the particles is in.A. Stable equlibrium if y= R/2 B. Unstable equlibrium at y=R/2C. Stable equlibrium at y=R D. Unstable equlibrium at y=R

Dear student,

Since the charge is in equilibrium at heightabove the center of ring, it must carry charge same as that of the ring to stay in equilibrium under the weight of the mass and the electrostatic repulsion from the ring.

If the mass is dispaced below point, electrostatic repulsion will increase and will tend to relocate the charge to the same point. If it is displaced above, repulsion decreases and body again tends to relocate to center under action of relatively larger gravitational pull.

Hence it is in a stable equilibrium.