What are the properties of an equipotential surface?

Explanation

Properties of equipotential surfaces
(i)The work done to move a charge q between any two points A and B, `W=q(V_B-V_A)`.If the points A and B lie on the same equipotential surface ,work done is zero because `V_A=V_B`.
(ii)The electric field is normal to an equipotential surface.If it is not normal then there is a component of the field parallel to the surface.Then work must be done to move a charge between two points on the same surface.This is a contradiction ,.Therefore the field must always be normal to equipotential surface.