In cgs, the electric dipole potential of a dipole with electric dipole moment p is given by
where r is the distance from the dipole. In MKS,
where
is the permittivity of free space.
In polar coordinates, the electric field of an electric dipole in cgs is
and in MKS,
Doing a coordinate-independent calculation in cgs units,
Because p is a constant vector
Plugging (8), (9), and (10) into (7),
Therefore, in cgs,
and in MKS,
Then the force exerted by an imposed electric field E on the dipole is
Let two dipoles
and 
be at angles 
and 
measured from the line connecting the dipoles. Then the energy of interaction is
where
is the azimuth of relative to the 
plane.
The torque exerted on a dipole of dipole moment p in an electric field E is
(1)
where r is the distance from the dipole. In MKS,
(2)
where
is the permittivity of free space.In polar coordinates, the electric field of an electric dipole in cgs is
(3)
(4)
and in MKS,
(5)
(6)
Doing a coordinate-independent calculation in cgs units,
(7)
(8)
Because p is a constant vector
(9)
(10)
Plugging (8), (9), and (10) into (7),
(11)
Therefore, in cgs,
(12)
and in MKS,
(13)
Then the force exerted by an imposed electric field E on the dipole is
(14)
Let two dipoles
and be at angles and measured from the line connecting the dipoles. Then the energy of interaction is where
is the azimuth of relative to the plane.The torque exerted on a dipole of dipole moment p in an electric field E is
(15)
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