$A$ uniform current-carrying ring of mass $m$ and radius $R$ is suspended by a massless string as shown. $A$ uniform magnetic field $B_0$ exists in the region to keep the ring in a horizontal position. Determine the current $I$ in the ring.

$A$ coil in the shape of an equilateral triangle of side $l$ is suspended between the pole pieces of a permanent magnet such that $\vec{B}$ is in the plane of the coil. If due to a current $i$ in the triangle a torque $\tau$ acts on it,the side $l$ of the triangle is

$A$ circular coil of $20$ turns and radius $10\, cm$ is placed in a uniform magnetic field of $0.10\, T$ normal to the plane of the coil. If the current in the coil is $5\, A$,then the torque acting on the coil will be...... $Nm$.

$A$ square coil of side $10 \ cm$ having $200$ turns is placed in a uniform magnetic field of $2 \ T$ such that the plane of the coil is in the direction of the magnetic field. If the current through the coil is $3 \ mA$, then the torque acting on the coil is

Four wires of equal length are bent in the form of four loops $P, Q, R$ and $S.$ These are suspended in a uniform magnetic field and the same current is passed through them. The maximum torque will act on:

$A$ uniform magnetic field of $2 \times 10^{-3} \ T$ acts along the positive $Y$-direction. $A$ rectangular loop of sides $20 \ cm$ and $10 \ cm$ carrying a current of $5 \ A$ is placed in the $Y-Z$ plane. The current flows in an anticlockwise sense with reference to the negative $X$-axis. Find the magnitude and direction of the torque.