$A$ rigid wire consists of a semicircular portion of radius $R$ and two straight sections. The wire is partially immersed in a perpendicular magnetic field $B = B_0 \hat{k}$ as shown in the figure. The magnetic force on the wire if it carries a current $i$ is:

$A$ circular coil of wire carries a current. $PQ$ is a part of a very long wire carrying a current and passing close to the circular coil. If the directions of currents are those shown in the figure,what is the direction of the force acting on $PQ$?

$A$ square loop of length $L$ is placed with its edges parallel to the $XY$-axes. The loop carries a current $I$. If the magnetic field in the region varies as $B = B_0 \left(1 + \frac{xy}{L^2}\right) \hat{k}$,then the magnitude of the net force on the loop will be:

Two long wires carrying currents $I_1$ and $I_2$ are arranged as shown in the figure. The wire carrying current $I_1$ is along the $x$-axis. The other wire carrying current $I_2$ is parallel to the $y$-axis,passing through the point $(0, 0, d)$. Find the magnetic force exerted on a segment of length $dl$ of the second wire at the point $O_2(0, 0, d)$ due to the wire carrying current $I_1$.

Two $10 \; cm$ long,straight wires,each carrying a current of $5 \; A$,are kept parallel to each other. If each wire experiences a force of $10^{-5} \; N$,then the separation between the wires is $\dots \; cm$.

Two thin long parallel wires separated by a distance $b$ are carrying a current $i$ $A$ each. The magnitude of the force per unit length exerted by one wire on the other is