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

Two insulated circular loop $A$ and $B$ radius ' $a$ ' carrying a current of ' $\mathrm{I}$ ' in the anti clockwise direction as shown in figure. The magnitude of the magnetic induction at the centre will be :

A current loop consists of two identical semicircular parts each of radius $R,$ one lying in the $x-y$ plane and the other in $x-z$ plane. If the current in the loop is $i.$ The resultant magnetic field due to the two semicircular parts at their common centre is

A circular coil of wire consisting of $100$ turns, each of radius $8.0\; cm$ carries a current of $0.40\, A$. What is the magnitude of the magnetic field $B$ at the centre of the coil?

Two circular coils $P$ and $Q$of $100$ turns each have same radius of $\pi \mathrm{cm}$. The currents in $\mathrm{P}$ and $\mathrm{R}$ are $1 \mathrm{~A}$ and $2 \mathrm{~A}$ respectively. $\mathrm{P}$ and $\mathrm{Q}$ are placed with their planes mutually perpendicular with their centers coincide. The resultant magnetic field induction at the center of the coils is $\sqrt{\mathrm{x}} \mathrm{mT}$, where X=___.

$\left[\text { Use } \mu_0=4 \pi \times 10^{-7} \mathrm{TmA}^{-1}\right]$

Three infinite wires are arranged in space in three dimensions.(along $x, y$ and $z$ axis) as shown. Each wire carries current $i$ . Find magnetic field at $A$