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 × 10–6 kg m2 . If the magnitude of magnetic moment of the needle is x × 10–5 Am2 , then the value of ‘x’ is :
1
5 π2
2
128 π2
3
50 π2
4
1280 π2
5
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