$A$ circular coil of radius $R$ carries an electric current. The magnetic field due to the coil at a point on the axis of the coil located at a distance $r$ from the centre of the coil,such that $r \gg R$,varies as:

Two circular loops having same radius $[ R = 10 \, cm ]$ and same current $[ I = \frac{7}{2} \, A ]$ are placed along the same axis as shown. If the distance between their centers is $[ 10 \, cm ]$,find the net magnetic field at point $P$ located at the midpoint between them.

The magnetic field at the centre $O$ of a wire loop formed by two semicircular wires of radii $R_1=2 \pi \text{ m}$ and $R_2=4 \pi \text{ m}$ carrying current $I=4 \text{ A}$ as per the figure given below is $\alpha \times 10^{-7} \text{ T}$. The value of $\alpha$ is . . . . . . . (Centre $O$ is common for all segments)

Two infinitely long wires, each carrying a current $I = 10 \ A$, are bent to form a right angle as shown in the figure. Find the magnetic induction at point $O$. $\left[\mu_0 = 4\pi \times 10^{-7} \ H \ m^{-1}\right]$

Write the formula for the magnetic field at a perpendicular distance $r$ from a finite current-carrying wire.

$A$ current-carrying wire in its neighborhood produces: