Dipole moment (p) = 3 × 10-8 Cm
The electric field of intensity (E) = 104 N/C
At stable equilibrium (θ1) = 0º
At unstable equilibrium (θ2) = 180º
Work done in a rotating dipole is given by
W = PE (cos θ1 – cos θ2)
= (3 × 10-8)(104) (cos 0º – 180º)
= 3 × 10-4 [1 – (-1)] = 6 × 10-4 J