$A$ square loop of side $a$ hangs from an insulating hanger of a spring balance. The magnetic field of strength $B$ exists only at the lower edge. It carries a current $I$. Find the change in the reading of the spring balance if the direction of current is reversed.

In an experiment,setup $A$ consists of two parallel wires which carry currents in opposite directions as shown in the figure. $A$ second setup $B$ is identical to setup $A$,except that there is a metal plate between the wires. Let $F_A$ and $F_B$ be the magnitude of the force between the two wires in setup $A$ and setup $B$,respectively.

$A$ wire carrying a steady current $I$ is kept in the $x$-$y$ plane along the curve $y=A \sin \left(\frac{2 \pi}{\lambda} x\right)$. $A$ magnetic field $B$ exists in the $z$-direction. The magnitude of the magnetic force on the portion of the wire between $x=0$ and $x=\lambda$ is

$A$ rectangular loop of wire,supporting a mass $m$,hangs with one end in a uniform magnetic field $\overrightarrow{B}$ pointing into the plane of the paper. $A$ clockwise current $i$ is set up such that $i > mg/Ba$,where $a$ is the width of the loop. Then:

Two parallel wires $1 \text{ m}$ apart carry currents of $1 \text{ A}$ and $3 \text{ A}$ respectively in opposite directions. The force per unit length acting between these two wires is

$A$ straight current-carrying conductor is kept along the axis of a circular loop carrying current. The force exerted by the straight conductor on the loop is