As shown in the above figure We want to find out Electric Field Intensity due to an Electric Dipole at a Point M which is on the Equitorial line and at a distance r from the center of a dipole.
Where is the Electric Field Intensity at M due to charges respectively.
So
Using
And
then (This is the value of when the dipole is placed in the vacuum.)
If the dipole is placed in the medium having the permittivity as
Then
Note: Here the direction of the electric field E is opposite to the direction of .