MP Board · Class 12 · Physics · Electric Charges and FieldsWrite the formula for the torque acting on an electric dipole placed in a uniform electric field. Under what condition is this torque maximum?

The torque acting on an electric dipole of dipole moment $\vec{p}$ placed in a uniform electric field $\vec{E}$ is given by $\vec{\tau} = \vec{p} \times \vec{E}$, or in magnitude $\tau = p E \sin\theta$, where $\theta$ is the angle between $\vec{p}$ and $\vec{E}$. The torque is maximum when $\theta = 90^\circ$ ($\sin 90^\circ = 1$), meaning the dipole is oriented perpendicular to the electric field lines, giving $\tau_{\text{max}} = p E$.