A neutral metal bar moves at a constant velocity $\mathrm{v}$ to the right through a region of uniform magnetic field directed out the page, as shown. Therefore,

 

A magnetic field$\overrightarrow{B}=B_0 \hat{\mathrm{j}} ,$ exists in the region $a<x<2a\text{ and } \overrightarrow{B}=–B_0 \hat{\mathrm{j}} ,$ in the region $2a<x<3a,$ where $B_0$ is a positive constant. A positive point charge moving with a velocity$\overrightarrow{V}= v_0 \hat{\mathrm{i}} ,$ where $v_0$ is a positive constant, enters the magnetic field at $x=a.$ The trajectory of the charge in this region can be like.

A particle of mass $m$ and charge $q$, moving with velocity $V$ enters region II normal to the boundary as shown in the figure. Region II has a uniform magnetic field $B$ perpendicular to the plane of the paper. The length of the region II is $l$. Choose the correct choice(s).

A thin flexible wire of length $L$ is connected to two adjacent fixed points carries a current $I$ in the clockwise direction, as shown in the figure. When system is put in a uniform magnetic field of strength $B$ going into the plane of paper, the wire takes the shape of a circle. The tension in the wire is

A long insulated copper wire is closely wound as a spiral of$N$ turns. The spiral has inner radius $a$ and outer radius$b$. The spiral lies in the X-Y plane and a steady current I flows through the wire. The Z component of the magnetic field at the center of the spiral is

A loop carrying current I lies in the x-y plane as shown in the figure. the unit vector $\hat{\mathrm{k}}$ is coming out of the plane of the paper. the magnetic moment of the current loop is :