Two long straight wires are set parallel to each other. Each carries a current $i$ in the same direction and the separation between them is $2r$. The intensity of the magnetic field midway between them is

The magnetic field due to a current-carrying circular coil on its axis at a distance of $\sqrt{2} \,d$ from the centre of the coil is $B$. If $d$ is the diameter of the coil, then the magnetic field at the centre of the coil is: (in $B$)

Two parallel wires of equal lengths are separated by a distance of $3 \text{ m}$ from each other. The currents flowing through the first and second wire are $3 \text{ A}$ and $4.5 \text{ A}$ respectively in opposite directions. The resultant magnetic field at the midpoint of both the wires is ($\mu_0$ = permeability of free space).

$A$ battery is connected between two points $A$ and $B$ on the circumference of a uniform conducting ring of radius $r$ and resistance $R$. One of the arcs $AB$ of the ring subtends an angle $\theta$ at the centre. The value of the magnetic induction at the centre due to the current in the ring is

Two infinite wires bent in the form of an $L$ shape carry current $I$ as shown. What is the magnetic field at $O$?

$A$ current of $8 \text{ A}$ each flows in opposite directions in two parallel conducting wires placed at a distance of $30 \text{ cm}$. The magnitude of the magnetic field at the midpoint between the two wires is . . . . . . $\mu \text{T}$. (Given: $\frac{\mu_0}{4\pi} = 10^{-7} \text{ N/A}^2$)