Two long parallel wires carrying equal current separated by $1\,m$,exert a force of $2 \times 10^{-7}\,N/m$ on one another. The current flowing through them is

Three long straight wires are carrying current as shown in the diagram. The magnetic force per unit length on wire $Q$ is $..... \times 10^{-7} \ N/m$.

$A$ current $i = 2 \, A$ flows through a wire frame as shown in the figure. The frame is a combination of two equilateral triangles $ACD$ and $CDE$ with side length $1 \, m$. It is placed in a uniform magnetic field $B = 4 \, T$ acting perpendicular to the plane of the frame. The magnitude of the net magnetic force acting on the frame is.......$N$.

For the circuit shown in the figure,the direction and magnitude of the force on the segment $PQR$ is:

$AB$ and $CD$ are smooth parallel rails,separated by a distance $l$,and inclined to the horizontal at an angle $\theta$. $A$ uniform magnetic field of magnitude $B$,directed vertically upwards,exists in the region. $EF$ is a conductor of mass $m$,carrying a current $i$. For $EF$ to be in equilibrium,

$A$ thin uniform rod with negligible mass and length $l$ is attached to the floor by a frictionless hinge at point $P$. $A$ horizontal spring with force constant $k$ connects the other end to a wall. The rod is in a uniform magnetic field $B$ directed into the plane of the paper. What is the extension in the spring in equilibrium when a current $i$ is passed through the rod in the direction shown? Assume the spring is initially at its natural length.