Question

The field line and equipotential surfaces are:
(A) Perpendicular
(B) Parallel
(C) Inclined at any angle
(D) None of the above

Answer 1

Here field line refers to the electric field lines and equipotential surface refers to the surface in which at every point the value of electric potential is the same. A surface can be equipotential when the body has a constant charge and all of that lies on the surface. The electric field lines come out of the positive charge and it goes inside for the case of the negative charge. The electric field lines tell us about the strength of the magnitude of electric charge.

Complete answer:
The electric field lines are always perpendicular to the equipotential surface. Had they not been perpendicular then there would be present the horizontal component of the electric field and in case we want to move a charge from one point to another on the equipotential surface, then work has to be done. But for an equipotential surface, no work is done in moving the charge from one point to another. Thus, the electric field lines are always perpendicular to the equipotential surface.

So, the correct option is A.

Note: A field line is drawn tangential to the net at a point. Thus, at any point, the tangent to the electric field line matches the direction of the electric field at that point. Secondly, the relative density of field lines around a point corresponds to the relative strength (magnitude) of the electric field at that point. In other words, if you see more electric field lines in the vicinity of point A as compared to point B, then the electric field is stronger at point A.