Obtain an expresssion for intensity of electric field in end on position. i.e., axial position of an electric dipole.  

Let an electric dipole is taken which constitutes (+q) and (- q) charge separated by the distance 2l.

Let from the mid point of the dipole at a distance ‘r’ is the point P at intensities due to (+q) and (-q) charge respectively.


direction along the dipole axis. 

E₂ =  direction opposite to the dipole axis. 

Resultant electric field intensity E = E₁ - E₂