Three long,straight and parallel wires carrying currents are arranged as shown in the figure. The wire $C$ which carries a current of $5.0\, A$ is so placed that it experiences no force. The distance of wire $C$ from wire $D$ is (in $, cm$)

$A$ wire $X$ of length $50 \; cm$ carrying a current of $2 \; A$ is placed parallel to a long wire $Y$ of length $5 \; m$. The wire $Y$ carries a current of $3 \; A$. The distance between the two wires is $5 \; cm$ and the currents flow in the same direction. The force acting on the wire $X$ due to wire $Y$ is:

$A$ long straight wire is carrying current $I_1$ in the $+z$ direction. The $x-y$ plane contains a closed circular loop carrying current $I_2$ and does not encircle the straight wire. The net force on the loop will be:

Suppose an isolated north pole is kept at the centre of a circular loop carrying an electric current $i$. The magnetic field due to the north pole at a point on the periphery of the wire is $B$. The radius of the loop is $a$. The force on the wire is

Two parallel conductors carrying unequal currents in the same direction . . . . . .

Two free parallel wires carrying currents in opposite directions: