A current of $10 \mathrm{A}$ flows through two long parallel wires. The magnetic force on each wire is $2\times {10}^{-3} \mathrm{N} {\mathrm{m}}^{-1}$. If the current is doubled and separation between them is halved, then magnetic force per unit length of each wire becomes,

Three long straight wires carrying currents are arranged according to figure. Magnetic force on $10 \mathrm{cm}$ part of the wire $Q$ is,

A rectangular loop $ABCD$ is placed near an infinite length current carrying wire. Magnetic force on the loop is,

A wire of length '$\mathcal{l}$’ carries a current bent into various regular polygons shown below. Find magnetic moment in terms of length of the wire. Circular loop.