A charge $q$ is moving in a circle of radius $r$ with speed $v.$ Find magnetic field at centre of loop.

Find out the magnetic field at point $P$ in the following cases.

$\left(\mathrm{a}\right)$  Circular loop Iving in the $x-v$ plane

$\left(\mathrm{b}\right)$  Circular loop turned by $90°$ in anticlockwise direction

A spiral of $20$ turns with inner radius $R$ and outer radius $2R$ is placed as shown in figure. If the current is $i,$ find magnetic field at the centre of spiral.

Find $\oint \overrightarrow{B}·\overrightarrow{dl}$ over following loops (direction in which integration has to be performed is indicated by arrows)

Two infinite sheets of current are carrying current $\lambda$ per unit length as shown in figure. Find magnetic field at points $A, B$ and $C.$

A solid thin wire is located inside two $co$-axial long cylindrical shells, each carrying current $i$ as shown in figure. Assuming wires to be infinitely long, find magnetic field at a point which is at a distance $x$ from the axis. Assume that $a<x<b.$