$A$ circular coil carrying a current of $2.5 \ A$ is free to rotate about an axis in its plane perpendicular to an external magnetic field. When the coil is made to oscillate, the time period of oscillation is $T$. If the current through the coil is $10 \ A$, the time period of oscillation is

$A$ rectangular coil of $400$ turns and $10^{-2} \ m^2$ area, carrying a current of $0.5 \ A$ is placed in a uniform magnetic field of $1 \ T$ such that the plane of the coil makes an angle of $60^{\circ}$ with the direction of the magnetic field. The initial moment of force acting on the coil in $Nm$ is

Which of the following loops is in stable equilibrium?

$A$ thin stiff insulated metal wire is bent into a circular loop with its two ends extending tangentially from the same point of the loop. The wire loop has mass $m$ and radius $r$ and it is in a uniform vertical magnetic field $B_0$,as shown in the figure. Initially,it hangs vertically downwards,because of acceleration due to gravity $g$,on two conducting supports at $P$ and $Q$. When a current $I$ is passed through the loop,the loop turns about the line $PQ$ by an angle $\theta$ given by

Two identical conducting wires $A$ and $B$ of same dimensions and same material are bent in the form of circular coils. Wire $A$ consists of a single turn,whereas wire $B$ consists of $2$ turns. Both these wires are then suspended in a uniform magnetic field with their planes parallel to one another,and the same current is passed through them. Which statement is correct?

The torque required to hold a small circular coil of $10$ turns, area $1 \,mm^{2}$ and carrying a current of $\left(\frac{21}{44}\right) \,A$ in the middle of a long solenoid of $10^{3} \,turns/m$ carrying a current of $2.5 \,A$, with its axis perpendicular to the axis of the solenoid is