The magnetic induction at the centre of a current-carrying circular coil of radius $10 \, cm$ is $5\sqrt{5}$ times the magnetic induction at a point on its axis. The distance of the point from the centre of the coil (in $cm$) is

$A$ long wire is bent into a circular coil of one turn and then into a circular coil of smaller radius having $n$ turns. If the same current is passed in both the cases, the ratio of magnetic field produced at the centre for one turn to that of $n$ turns is

Two long current-carrying conductors are placed parallel to each other at a distance of $8 \, cm$ between them. The magnitude of the magnetic field produced at the mid-point between the two conductors due to the current flowing in them is $300 \, \mu T$. The equal current flowing in the two conductors is ...............

Two concentric coils each of radius equal to $4 \pi \text{ cm}$ are placed at right angles to each other. If $10 \text{ A}$ and $24 \text{ A}$ are the currents flowing through the coils,respectively,the magnetic induction at the center of the coils will be

$A$ circular loop is kept in the vertical plane that contains the north-south direction. It carries a current that is towards the south at the topmost point. Let $A$ be a point on the axis of the circle to the east of it and $B$ be a point on this axis to the west of it. The magnetic field due to the loop is:

An electron revolves in a circle of radius $0.4 \text{ Å}$ with a speed of $10^6 \text{ m/s}$ in a hydrogen atom. The magnetic field produced at the centre of the orbit due to the motion of the electron (in Tesla) is: $\left[\mu_0 = 4\pi \times 10^{-7} \text{ H/m}, q = 1.6 \times 10^{-19} \text{ C}\right]$