Q. An electric dipole of moment $'p'$ is placed in an electric field of intensity $'E^{'}.$ The dipole acquires a position such that the axis of the dipole makes an angle $\theta$ with the direction of the field. Assuming that the potential energy of the dipole to be zero when $\theta = 90^{o}$, the torque and the potential energy of the dipole will respectively be
A) $pE\sin\theta,\ - pE\cos\theta$
B) $pE\sin\theta,\ - 2pE\cos\theta$
C) $pE\sin\theta,\ 2pE\cos\theta$
D) $pE\cos\theta,\ - pE\cos\theta$
Explanation
(a) $\tau = pE\sin\theta$
$U = - pE\cos\theta$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.