A magnetic needle of magnetic moment 6.7 × 10^-2 Am^2 and moment of inertia 7.5 × 10^-6 kg m^2 is performing simple harmonic oscillations in a…

A magnetic needle of magnetic moment $\displaystyle 6.7 \times 10^{-2} \mathrm{Am}^2$ and moment of inertia $\displaystyle 7.5 \times 10^{-6} \mathrm{~kg} \mathrm{~m}^2$ is performing simple harmonic oscillations in a magnetic field of $\displaystyle 0.01$ T. Time taken for $\displaystyle 10$ complete oscillations is :