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

$A$ square coil of side $a$ carries a current $I$. The magnetic field at the centre of the coil is

The radius of a circular coil is $R$ and it carries a current of $I$ ampere. The intensity of the magnetic field at a distance $x$ on the axis from the centre $(x >> R)$ will be:

$A$ long straight wire carrying a current of $30 \ A$ is placed in an external uniform magnetic field of induction $4 \times 10^{-4} \ T$. The magnetic field is acting parallel to the direction of current. The magnitude of the resultant magnetic induction in tesla at a point $2.0 \ cm$ away from the wire is $(\mu_0 = 4 \pi \times 10^{-7} \ H/m)$.

Give the differences between Biot-Savart law and Coulomb's law.

If a wire of length $L$ carrying a current $i$ is bent in the shape of a semi-circular arc as shown in the figure,then the magnetic field at the centre of the arc is