A spherical shell of radius $\text{'}R\text{'}$ and uniformly charged with charge $\text{'}Q\text{'}$ is rotating about its axis with frequency $\text{'}f\text{'}$. Find the magnetic moment of the sphere.

Four wires each of length $2.0 \mathrm{metre}$ are bent into four loops $P, Q, R$ and $S$ and then suspended into a uniform magnetic field. The same current is passed in each loop. Which statement is correct?

A triangular loop of side $l$ carries a current $I$. It is placed in a magnetic field $B$ such that the plane of the loop is in the direction of $B$. The torque on the loop is

A current carrying loop is free to turn in a uniform magnetic field. The loop will then come into equilibrium when its plane is inclined at

A current $i$ flows in a circular coil of radius $r$. If the coil is placed in a uniform magnetic field $B$ with its plane parallel to the field, magnitude of the torque that acts on the coil is