Define an equipotential surface. Draw equipotential surfaces :
`(i)` in the case of single point charge and
`(ii)` in a constant electric field in `Z`-direction.
Why the equpotential surfaces about a single charge are not equidistant ?
`(iii)` Can electric field exist tangential to an equipotential surface ? Given reason.

Explanation

`(i)`
`(ii)` A surface where potential at every point is same called equipotential surface.
Because electric field goes on decreasing as we move away from charge. So, potential also decreases.

`(iii)` Let , electric field is tangent to equipotential surface, then work has to be done in moving a charge over surface but work done in moving a charge over an equipotential surface is zero so it contradicts our assumption.