A closed current-carrying loop having a current I is having area A. Magnetic moment of this loop is defined as `vec(mu) = vec(IA)` where direction of area vector is towards the observer if current is flowing in anticlockwise direction with respect to the observer. If this loop is placed in a uniform magnetic field `vec(B)`, then torque acting on the loop is given by `vec(tau) = vec(mu) xx vec(B)`. Now answer the following questions:
Consider the situation shown in Fig., ring is having a uniformly distributed positive charge. Magnetic field is perpendicular to the axis of ring. Now ring is rotated in anticlockwise direction as seen from left hand side direction of magnetic torque acting on the ring is

Options

A. Parallel to `vec(B)`
B. Parallel to axis of ring
C. Going into plane of paper
D. Coming out of plane of paper

Answer

C

Explanation

M will be directed towards left, so torque will be along the axis going into the plane of paper.