Potential at a
point is arbitrary to within an additive constant, since it is the potential
difference between two points which is physically significant If potential
at infinity is chosen to be zero; potential at a point with position vector
r due to a point charge Q placed at the origin is given is given by
1
( )
4
o
Q
V
r
ε
=
π
r
3 The electrostatic potential at a point with position vector r due to a
point dipole of dipole moment p placed at the origin is
ˆ2
1
( )
=4 ε
π
p r
r
o
V
r
The result is true also for a dipole (with charges –q and q separated by
2a)  for r >> a