Physics - Electrostatics Question with Solution | TestHub

The potential energy of an electric dipole in a uniform electric field is given by $U=-pE\cos \theta$, where $\theta$ is the angle between the dipole moment $\overrightarrow{p}$ and the electric field $\overrightarrow{E}$. Given $U=-pE/2$. Therefore, $-pE/2=-pE\cos \theta$. This implies $\cos \theta =1/2$. The angle $\theta$ is $60^{\circ }$.