A magnet of magnetic moment M and moment of inertia I oscillates with time period T in a uniform magnetic field B. It is replaced by another magnet having magnetic moment 4M and moment of inertia 9I.
The time period of the new magnet is:

Question

A magnet of magnetic moment M and moment of inertia I oscillates with time period T in a uniform magnetic field B. It is replaced by another magnet having magnetic moment 4M and moment of inertia 9I.

The time period of the new magnet is:

G1 Physics · Accepted Answer

For small angular oscillations, T ∝ √(I/M) when B is unchanged. Thus, T'/T = √[(I'/M')/(I/M)] = √[(9I/4M)(M/I)] = √(9/4) = 3/2. Hence, T' = 3T/2.