A dipole comprises of two charged particles of identical magnitude q… | JEE Main 2023 (6 Apr, Shift 2)

Q48JEE Main 2023 · 6 APR · SHIFT 2Difficult

Electric Dipole

A dipole comprises of two charged particles of identical magnitude $q$ and opposite in nature. The mass 'm' of the positive charged particle is half of the mass of the negative charged particle. The two charges are separated by a distance ' $l$ '. If the dipole is placed in a uniform electric field ' $\vec{E}$ '; in such a way that dipole axis makes a very small angle with the electric field, ' $\vec{E}$ '. The angular frequency of the oscillations of the dipole when released is given by:

Show answer and solution

Answer: (a)

Masses $m$ (+) and $2m$ (−): centre of mass is $\frac{2l}{3}$ from $m$ and $\frac{l}{3}$ from $2m$ .
$I = m\left(\frac{2l}{3}\right)^2 + 2m\left(\frac{l}{3}\right)^2 = \frac{2ml^2}{3}$
Restoring torque $\tau \approx qlE\,\theta$ , so $\omega^2 = \frac{qlE}{2ml^2/3} = \frac{3qE}{2ml}$
So the answer is (a) $\sqrt{\frac{3qE}{2ml}}$ .

Report a mistake

Electric Dipole question from JEE Main 2023 (6 Apr, Shift 2)

More questions on Electric Dipole