Thus, we can
expect to get approximately the same result as above by directly using
the formula for electric field at a far-away point on the axis of a dipole For a dipole consisting of charges ± q, 2a distance apart, the electric
field at a distance r from the centre on the axis of the dipole has a
magnitude
E
p
r
=
2
4
0
3
πε
(r/a >> 1)
where p = 2a q is the magnitude of the dipole moment The direction of electric field on the dipole axis is always along the
direction of the dipole moment vector (i e