A charge particle $A$ of charge $q = 2\,\, C$ has velocity $v = 100\,\, m/s.$ When it passes through point Aand has velocity in the direction shown. The strength of magnetic field at point $B$ due to this moving charge is.......$\mu T$ $(r = 2\,\, m).$

Two very long, straight and insulated wires are kept at $90^o$ angle from each other In $xy -$ plane as shown in the figure. These wires carry current of equal magnitude $I$, whose directions are shown in the figure. The net magnetic field at point $P$ will be

The magnetic field at the centre of a wire loop formed by two semicircular wires of radii $R_1=2 \pi\  \mathrm{m}$ and $R_2=4 \pi\  \mathrm{m}$ carrying current $I=4 \mathrm{~A}$ as per figure given below is $\alpha \times 10^{-7} \mathrm{~T}$. The value of $\alpha$ is___________ (Centre $\mathrm{O}$ is common for all segments)

The current of $1\,A$ is passed through a hexagonal conducting wire of side $1\,m$ . The magnetic induction at its centre $O$ in $Wb/m^2$ will be

An electron in a hydrogen atom revolves around its nucleus with a speed of $6.76 \times 10^6\,ms ^{-1}$ in an orbit of radius $0.52\,\mathring A$. The magnetic field produced at the nucleus of the hydrogen atom is $......T$.

A coil of one turn is made of a wire of certain length and then from the same length a coil of two turns is made. If the same current is passed in both the cases, then the ratio of the magnetic inductions at their centres will be