Physics

Problem

A circular coil has moment of inertia

0.8 \text{ kg m}^2

around any diameter and is carrying current to produce a magnetic moment of

20 \text{ 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 \text{ T}

is applied along the vertical, it starts rotating around its horizontal diameter. The angular speed the coil acquires after rotating by

60^\circ

will be : a.

10 \text{ rad s}^{-1}

10\pi \text{ rad s}^{-1}

20\pi \text{ rad s}^{-1}

20 \text{ rad s}^{-1}