In the figure,the magnetic induction at the centre $O$ due to the current in the straight portion $AB$ will be:

$A$ very long wire carrying a current $I = 4 \sqrt{2} \, A$ is bent at a right angle. The magnitude of the magnetic field $(|B|)$ at a point $P$ lying on a line perpendicular to the bent wire at a distance $d = 20 \, cm$ from the point of the bending will be (Let $\mu_0 = 4 \pi \times 10^{-7} \, H/m$): (in $\, \mu T$)

The magnetic field at the center of a circular coil of radius $0.1\, m$ having $1000$ turns and carrying a current of $0.1\, A$ is:

$A$ current $i$ is flowing through the loop. The direction of the current and the shape of the loop are as shown in the figure. The magnetic field at the centre $M$ of the loop is $\frac{\mu_{0} i}{R}$ times
$(MA=R, MB=2 R, \angle DMA=90^{\circ})$

Define the law for finding the direction of a magnetic field due to a circular current loop.

Connecting wires carrying currents in opposite directions are twisted together in electrical appliances in order to reduce: