Two long and parallel straight wires $A$ and $B$ carrying currents of $8.0 \, A$ and $5.0 \, A$ in the same direction are separated by a distance of $4.0 \, cm$. Estimate the force on a $10 \, cm$ section of wire $A$.

$A, B$ and $C$ are parallel conductors of equal length carrying currents $I, I$ and $2I$ respectively. The distance between $A$ and $B$ is $x$. The distance between $B$ and $C$ is also $x$. If $F_1$ is the force exerted by $B$ on $A$ and $F_2$ is the force exerted by $C$ on $B$,choose the correct answer.

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

$A$ long straight wire carrying a current of $25 \ A$ rests on a table as shown in the figure. Another wire $PQ$ of length $1 \ m$ and mass $2.5 \ g$ carries the same current but in the opposite direction. The wire $PQ$ is free to slide up and down. To what height $h$ will $PQ$ rise?

$A$ $100$ turn rectangular coil $ABCD$ (in $xy$-plane) is hung from one arm of a balance (Figure). $A$ mass of $500 \text{ g}$ is added to the other arm to balance the weight of the coil. $A$ current of $4.9 \text{ A}$ passes through the coil and a constant magnetic field of $0.2 \text{ T}$ acting inward (in $xz$-plane) is switched on such that only arm $CD$ of length $1 \text{ cm}$ lies in the field. How much additional mass '$m$' must be added to regain the balance?

Two parallel,long wires are kept $0.20 \, m$ apart in a vacuum,each carrying a current of $x \, A$ in the same direction. If the force of attraction per meter of each wire is $2 \times 10^{-6} \, N$,then the value of $x$ is approximately: