A dipole of dipole moment p is kept at the centre of a ring of radius R having charge Q. The dipole moment has direction along the axis of the ring. The electrostatic force on the ring due to the dipole is

Each point on the ring is on a perpendicular bisector to the given dipole. The electric field at each point on the ring is directed opposite to the dipole moment. Force on any small segment of the ring is directed opposite to the dipole momentC