A magnetic dipole of magnetic moment $6 \times 10^{-2} \, {Am^{2}}$ and moment of inertia $12 \times 10^{-6} \, {kg\, m^{2}}$ performs oscillations in a magnetic field of $2 \times 10^{-2} $ T. The time taken by the dipole to complete $20$ oscillations is $( \pi \simeq 3)$