Three long straight wires are connected parallel to each other across a battery of negligible internal resistance. The ratio of their resistances are $3 : 4 : 5$. What is the ratio of distances of middle wire from the others if the net force experienced by it is zero

An arrangement of three parallel straight wires placed perpendicular to plane of paper carrying same current $'I'$ along the same direction as shown in figure. Magnitude of force per unit length on the middle wire $'B'$ is given by 

Obtain equation for force between two parallel currents carrying wire.

A $3.0\; cm$ wire carrying a current of $10 \;A$ is placed inside a solenoid perpendicular to its axis. The magnetic field inside the solenoid is given to be $0.27\; T$. What is the magnetic force on the wire?

$AB$ 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 $i$, if $B$ is normal to the plane of the rails

A rectangular loop carrying a current $i$ is situated near a long straight wire such that the wire is parallel to the one of the sides of the loop and is in the plane of the loop. If a steady current $I$ is established in wire as shown in figure, the loop will