The magnetic moment and moment of inertia of a magnetic needle as shown are, respectively, \(1.0 \times 10^{-2} \, \text{A} \, \text{m}^2\) and \(\frac{10^{-6}}{\pi^2} \, \text{kg} \, \text{m}^2\). If it completes 10 oscillations in 10 s, the magnitude of the magnetic field is:
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