The torque acting on a coil carrying current '$I$',having '$n$' turns and area '$A$',situated parallel to a magnetic field of induction '$B$' is:

The $(\tau - \theta)$ graph for a current-carrying coil in a magnetic field is:

$A$ small circular loop of conducting wire has radius $a$ and carries current $I$. It is placed in a uniform magnetic field $B$ perpendicular to its plane such that when rotated slightly about its diameter and released,it starts performing simple harmonic motion of time period $T$. If the mass of the loop is $m$,then find the expression for $T$.

$A$ uniform magnetic field of $3000\,G$ is established in the positive $z-$ direction. $A$ rectangular loop of sides $10\,cm$ and $5\,cm$ carries a current of $12\,A$. The loop is placed in the $xy-$ plane as shown in the figure. What is the magnitude of the torque on the loop?

$A$ disc of radius $r$ carrying a positive charge $q$ is rotating with an angular speed $\omega$ in a uniform magnetic field $B$ about a fixed axis as shown in the figure,such that the angle made by the axis of the disc with the magnetic field is $\theta$. The torque applied by the axis on the disc is:

The torque required to hold a small circular coil of $10$ turns,$2 \times 10^{-4} \ m^2$ area,and carrying $0.5 \ A$ current in the middle of a long solenoid of $10^3$ turns per meter carrying $3 \ A$ current,with its axis perpendicular to the axis of the solenoid,is: