Oscillation of a Magnetic Needle

2024 1 question

1. In a uniform magnetic field of 0.049 T, a magnetic needle performs 20 complete oscillations in 5 seconds as shown. The moment of inertia of the needle is $9.8 \times 10^{-6}$ kg m$^2$. If the magnitude of magnetic moment of the needle is $x \times 10^{-5}$ Am$^2$, then the value of 'x' is;