A 250-turn rectangular coil of length 2.1 cm and width 1.25 cm carries a current of 85 $$\mu $$A and subjected to a magnetic field of strength 0.85 T. Work done for rotating the coil by 180^o against the torque is

A bar magnet is hung by a thin cotton thread in a uniform horizontal magnetic field and is in equilibrium state. The energy required to rotate it by 60^o is W. Now the torque required to keep the magnet in this new position is

The magnetic susceptibility is negative for

A rectangular coil of length 0.12 m and width 0.1 m having 50 turns of wire is suspended vertically in a uniform magnetic field of strength 0.2 weber/m². The coil carries a current of 2 A. If the plane of the coil is inclined at an angle of 30^o with the direction of the field, the torque required to keep the coil in stable equilibrium will be