A circular coil has moment of inertia 0 . 8 kg m 2 around any diameter and is carrying current to produce a magnetic moment of 20 Am 2 . The coil is kept initially in a vertical position and it can rotate freely around a horizontal diameter. When a uniform magnetic field of 4 T is applied along the vertical, it starts rotating around its horizontal diameter. The angular speed the coil acquires after rotating by 60 o will be :

Question

A circular coil has moment of inertia 0 . 8 kg m 2 around any diameter and is carrying current to produce a magnetic moment of 20 Am 2 . The coil is kept initially in a vertical position and it can rotate freely around a horizontal diameter. When a uniform magnetic field of 4 T is applied along the vertical, it starts rotating around its horizontal diameter. The angular speed the coil acquires after rotating by 60 o will be :, 10 rad s - 1, 10 π rad s - 1, 20 π rad s - 1, 20 rad s - 1

MARKS App · Accepted Answer

From energy conservation 1 2 Iω 2 = U n - U t = - MBcos 60 ° - ( - MB ) MB 2 = 1 2 Iω 2 20 × 4 2 = 1 2 ( 08 ) m 2 100 = ω 2 ω = 10 rad

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