What is the angle between the equipotential surface and the electric field is:
A. 90 always
B. 0 always
C. 0 to 90
D. 0 to 180

Hint: First of all we should know about the electric field and the equipotential surface. Hence Electric field is a region around a charged particle or object within which its influence or a force would be experienced or exerted on other charged particles or objects. Equipotential surfaces are the surfaces which have the equal potential all around the body.

Complete answer:
The equipotential surfaces are always perpendicular to the electric field. These lines create the equipotential surfaces in three dimensions. No work is required in order to move along an equipotential surface, since such movement is always perpendicular to the electric field.

Why is it not possible that the electric field have components along an equipotential line?
This is because the electric field is defined as the (negative) gradient of the electrostatic potential, which means that the only electric field is allowed at a point on an equipotential must be perpendicular to the equipotential surface, otherwise it would have a non-zero component along the surface.

Hence the correct answer is (A), which is 90 always.

Note:The electric field is always perpendicular to an equipotential surface. The main advantages of equipotential surfaces are that they can never intersect with each other. Thus, for a given point charge, the equipotential surfaces are always in concentric spherical shells.Equipotential surface’s direction is always from the high potential to low potential.