CBSE Class 12-science Answered

The Electric field at a point P on the axis of the dipole at a distance x from the center of the dipole as shown

          Electric field at P due to – q:

Where  is the unit vector in the positive x direction.

Electric field at P due to + q:

Hence, net electric field at P can be written as

Upon substitution and transposing we get

Assuming that the point P is at a very large distance from the centre of the dipole axis,

                   For, we can neglect  in the denominator

         Since the dipole moment is given as

Thus the expression for electric field at a point on the axis of the dipole becomes

                     (For)