Assertion: Electric field is aways directed perpendicular to an equipotential surface.
Reason: Equipotential surface is a surface on which at each point potential is same.

Options

A. If both assertion and reason are true and reson is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If assertion and reason both are false.

Answer

B

Explanation

On equipotential surface, the potential at each point is same throughout.
Let `vecE` be electric field of a point on equipotential surface. Then, samell work done in moving a test charge `q_(0)` through a small displacement along the surafce.
`dW = vecE. dvecr = (q_(0)vecE). dvecr`
Since, work in moving a test charge along an equipotential surface is always zero.
`(-q_(0)vecE). dvecr = 0` or `vecE. dvecr = 0`
Hence, electric field is directed perpendicualr to the surface.