Equipotential surfaces are always at right angles to the electric field.

Question

Quizplus · Accepted Answer

Equipotential surfaces are always perpendicular to electric field lines because the electric field is defined as the force per unit charge experienced by a small positive test charge, and work is only done when there is a component of force along the direction of motion. Since no work is done moving along an equipotential surface (the potential difference is zero), the electric field must be perpendicular to these surfaces to ensure that the component of force along the surface is zero.

Equipotential Surfaces Are Always at Right Angles to the Electric