Question

A bar magnet is oscillating in the earth's magnetic field with time period T. If its mass is increased four times then its time period will be:

• A. T/2
• B. T
• C. 2T
• D. 4T

Answer 1

The correct option is C 2T

We know $T=2\pi \sqrt{\frac{I}{M_h}}$

now $\frac{T_f}{T}=\sqrt{\frac{I_f}{I}}$ , when mass is increased to four time then $I_f=4I$

so $T_f=2T$