A bar-magnet of moment of inertia $49 \times 10^{-2}$ vibrates in a magnetic field of induction $0.5 \times 10^{-4}T.$ The time period of vibration is $8.8 \;s$. The magnetic moment of the bar magnet is

Question

\[\begin {array} {1 1} (a)\;350\; A-m^2 & \quad (b)\;490\;A-m^{2} \\ (c)\;3300\;A-m^{2} & \quad (d)\;5000\;A-m^2 \end {array}\]