A ring of radius R carries a uniformly distributed charge ` + Q. ` A point charge ` - q ` is placed on the axis of the ring at a distance ` 2R ` from its centre and than released. Will the charge -q execute a simple harmonic motion along the axis of the ring ?

Explanation

In this case, it can be shown that the force on the point charge -q is inversely proportional to the square of its distance from the centre of the ring. This is not the characteristics of a simple harmonic motion. So the particle will not execute a simple harmonic motion.