CBSE Class 12-science Answered

any surface over which the electric potential is same everywhere is called equipotential surface....

euipotential surface can be drawn through a space in which there is an electric field. As an example let us consider the electric field of an isolated point charge +q as shown in the figure...

the potential at any distance r from the chrage is

                                                   V = q/4πε_or

r -----> radius of the circle

q----> charge

the electric lines of force are everywhere at right angles to the equipotential surface because there is no potential gradient along any direction parallel to the surface and so no electric field parallel to the surface (E  = -dv/dr = 0) .this means that electric field E, and hence lines of force, are everywhere at right angles to the equipotential surface....