Q 12-05-051JEE MainJEE Main 2022 (27 Jul, Shift 1)Easy
Two bar magnets oscillate in a horizontal plane in earth's magnetic field with time periods of $3$ s and $4$ s respectively. If their moments of inertia are in the ratio of $3 : 2$ then the ratio of their magnetic moments will be
Answer: (B) $8 : 3$
$T = 2\pi\sqrt{\dfrac{I}{MB_H}}$, so $M \propto \dfrac{I}{T^2}$:
$$\frac{M_1}{M_2} = \frac{I_1}{I_2}\cdot\frac{T_2^2}{T_1^2} = \frac32\times\frac{16}{9} = \frac83$$
Solution by Sreeraj P, M.Sc Physics