The amount of work done by the
external torque will be given by
(
)
cos
cos
pE
θ
θ
0
1
=
−
(2 31)
This work is stored as the potential energy of the system We can
then associate potential energy U(q) with an inclination q  of the dipole Similar to other potential energies, there is a freedom in choosing the
angle where the potential energy U is taken to be zero