Q 12-01-085JEE MainJEE Main 2023 (13 Apr, Shift 1)Easy
Two charges of each magnitude $0.01\ \text{C}$ and separated by a distance of $0.4\ \text{mm}$ constitute an electric dipole. If the dipole is placed in an uniform electric field $\vec E$ of $10\ \text{dyne C}^{-1}$ making $30^\circ$ angle with $\vec E$, the magnitude of torque acting on dipole is
Answer: (D) $2.0\times10^{-10}\ \text{N m}$
$p=0.01\times4\times10^{-4}=4\times10^{-6}\ \text{C m}$; $E=10\ \text{dyne C}^{-1}=10^{-4}\ \text{N C}^{-1}$.
$\tau=pE\sin30^\circ=4\times10^{-6}\times10^{-4}\times0.5=2\times10^{-10}\ \text{N m}$.
Solution by Sreeraj P, M.Sc Physics