Two long parallel copper wires carry currents of $5\,A$ each in opposite directions. If the wires are separated by a distance of $0.5\,m$,then the force between the two wires is

$A$ $2 \, A$ current carrying straight metal wire of resistance $1 \, \Omega$, resistivity $2 \times 10^{-6} \, \Omega m$, area of cross-section $10 \, mm^2$ and mass $500 \, g$ is suspended horizontally in mid-air by applying a uniform magnetic field $\vec{B}$. The magnitude of $B$ is . . . . . . . $\times 10^{-1} \, T$ (given, $g=10 \, m/s^2$).

Find the force per unit length at point $P$. The current in the wire is $5 \, A$ and the distance between the parallel segments is $10 \, cm$.

$A$ massless square loop of wire of resistance $R$ supporting a mass $M$ hangs vertically with one of its sides in a uniform magnetic field $B$ directed outwards in the shaded region. $A$ d.c. voltage $V$ is applied to the loop. For what value of $V$ will the magnetic force exactly balance the weight of the supporting mass $M$? (side of loop $= L, g =$ acceleration due to gravity)

Two parallel conductors $A$ and $B$ of equal lengths carry currents $I$ and $10\, I$,respectively,in the same direction. Then

$A$ straight wire carrying a current $i_1 \, A$ runs along the axis of a circular loop carrying a current $i_2 \, A$. The force of interaction between the two current-carrying conductors is