Q 12-01-005NEETNEET 2023Top questionEasy
An electric dipole is placed at an angle of $30°$ with an electric field of intensity $2 \times 10^5\ \text{N C}^{-1}$. It experiences a torque equal to $4$ N m. Calculate the magnitude of charge on the dipole, if the dipole length is $2$ cm.
Answer: (D) $2$ mC
$\tau = pE\sin\theta = (q \cdot 2a)E\sin\theta$:
$$4 = q \times 0.02 \times 2 \times 10^5 \times \frac{1}{2} = 2000\,q$$
$$q = 2 \times 10^{-3}\ \text{C} = 2\ \text{mC}$$
Solution by Sreeraj P, M.Sc Physics