$A$ current of $1 \, A$ flows through an infinitely long straight wire. The magnetic field produced at a point $1 \, m$ away from it is:

$A$ loop $ABCDA$,carrying current $I=12 \ A$,is placed in a plane,consists of two semi-circular segments of radius $R_1=6 \pi \ m$ and $R_2=4 \pi \ m$. The magnitude of the resultant magnetic field at center $O$ is $k \times 10^{-7} \ T$. The value of $k$ is . . . . . . . (Given $\mu_0=4 \pi \times 10^{-7} \ Tm \ A^{-1}$)

$Weber/m^2$ is equal to

Apply the Biot-Savart law to find the magnetic field due to a circular current-carrying loop at a point on the axis of the loop.

An infinitely long wire carrying current $I$ is along the $Y$-axis such that its one end is at point $A(0, b)$ while the wire extends up to $+\infty$. The magnitude of the magnetic field strength at point $(a, 0)$ is:

Consider two thin identical conducting wires covered with very thin insulating material. One of the wires is bent into a loop and produces a magnetic field $B_1$ at its centre when a current $I$ passes through it. The second wire is bent into a coil with three identical loops adjacent to each other and produces a magnetic field $B_2$ at the centre of the loops when a current $I/3$ passes through it. The ratio $B_1 : B_2$ is