Calculate the potential energy of a point charge placed along the axis due to charge uniformly distributed along a ring of radius R. Sketch PE as a function of axial distance z from the center of the ring. Looking at the graph, can you see what would happen if is displaced slightly from the center of the ring?
Explanation:-
The potential energy of a point charge q is U and this point is placed at potential V,
A negatively charged particle is placed at the axis of the ring with charge Q
Let a be the radius of the ring
The electric potential at the axial distance is given as
The potential energy, U is given as
When z=infinity, U=0.
When z=0, U is given as