The direction of magnetic lines of force produced by passing a direct current in a conductor is given by

An infinitely long wire carrying $1 \ A$ current in the $+z$ direction is placed at $(1 \ cm, 1 \ cm)$. Another wire carrying $1 \ A$ in the $+x$ direction is placed at $y=1 \ cm$. If the magnetic field due to this configuration at the origin is $B$. Let $B_0$ be the magnitude of the field if only the wire at $(1 \ cm, 1 \ cm)$ was present,then $\frac{B}{B_0}$ is

In the hydrogen atom,the electron is making $6.6 \times 10^{15} \, r.p.s.$ If the radius of the orbit is $0.53 \times 10^{-10} \, m,$ then the magnetic field produced at the centre of the orbit is (in $Tesla$):

$A$ long wire carries a steady current. It is bent into a coil of one turn such that the magnetic induction at the centre is $B$. If the same wire is bent to form a coil of smaller radius with $n$ turns,then the new magnetic induction $B^{\prime}$ at the centre is:

The magnetic field at the centre $O$ due to the given structure is:

Two parallel wires of equal lengths are separated by a distance of $3 \text{ m}$ from each other. The currents flowing through the first and second wire are $3 \text{ A}$ and $4.5 \text{ A}$ respectively in opposite directions. The resultant magnetic field at the midpoint of both the wires is ($\mu_0$ = permeability of free space).