Question

What is an equipotential surface? Show that the electric field is always directed perpendicular to an equipotential surface.

Answer 1

equipotential surfaces any surface with same electric potential at every point is called an equipotential surface.

In this case the "altitude" is electric potential or voltage. Equipotential lines are always perpendicular to the electric field. In three dimensions, the lines form equipotential surfaces. Movement along an equipotential surface requires no work because such movement is always perpendicular to the electric field.