A magnetic needle has magnetic moment of $5 \times 10^{-2} Am^2$ and Moment of inertia $12 \times 10^{-6} Kgm^2$. It performs 60 oscillations in 1 minute when suspended in a magnetic field. What is the magnitude of the magnetic field?

$.01 \times 10^{-4} T$ $94.7 \times 10^{-4} T$ .01 G 4.7 G

$94.7 \times 10^{-4} T$

The correct answer is Option (2) → $94.7 \times 10^{-4} T$