Potential Energy of Dipole in a Uniform Electric Field
The work done in rotating the dipole from one orientation to another is stored in the form of energy called potential energy of dipole.
It is a scalar quantity.S.I. unit of potential energy is joule (J).
Work done to rotate the dipole electric field through an angle dθ against the torque is,
dW = τ dθ = pE sinθ dθ
Suppose, the dipole is rotated from orientation θ1 to θ2, then the total work done is given by,
If dipole is initially at right angle to 
i.e., θ1 = 90° and finally it makes an angle θ with i.e., θ2 = θ, then
i.e., θ1 = 90° and finally it makes an angle θ with i.e., θ2 = θ, thenW = – pE (cosθ – cos 90°)
W = – pE cosθ
This work done is equal to the potential energy U of the dipole.
Cases:
