An electric dipole of moment p is placed parallel to the uniform electric field. The amount of work done in rotating the dipole by 90 is-

Q. An electric dipole of moment p is placed parallel to the uniform electric field. The amount of work done in rotating the dipole by 90⁰ is-
(i) 2pE
(ii) pE
(iii) pE/2
(iv) Zero

Answer: (ii) pE

W = pE ( cosθ₁– cosθ₂ )

θ₁ =0°

θ₂ = 90°

W = pE (cos 0° – cos 90°)

W = pE (1 – 0) = pE