Which of the following graphs represents the variation of magnetic field $B$ with perpendicular distance $r$ from an infinitely long,straight conductor carrying current?

The magnetic field due to a current-carrying circular loop of radius $6 \text{ cm}$ at a point on the axis at a distance of $8 \text{ cm}$ from the centre is $27 \mu \text{T}$. The magnetic field at the centre of the current-carrying loop is: (in $\mu \text{T}$)

$A$ circular loop of radius $0.0157\,m$ carries a current of $2.0\,A$. The magnetic field at the centre of the loop is $(\mu_0 = 4\pi \times 10^{-7}\,T\cdot m/A)$.

If a wire of length $L$ forms a loop of radius $R$ and has $n$ turns,find the magnetic field at the center of the loop if the current flowing in the loop is $I$.

The magnetic field at the centre of a circular coil of radius $R$,carrying current $2 \ A$ is $B_1$. The magnetic field at the centre of another coil of radius $3R$ carrying current $4 \ A$ is $B_2$. The ratio $B_1: B_2$ is

$A$ wire has three different sections as shown in the figure. The magnitude of the magnetic field produced at the centre '$O$' of the semicircle by the three sections together is $(\mu_0 = \text{permeability of free space})$: