A current $I$ flows in an infinitely long wire with cross-section in the form of a semicircular ring of radius $R$ . The magnitude of the magnetic induction along its axis is
$\frac{{{\mu _0}I}}{{{\pi ^2}R}}$
$\frac{{{\mu _0}I}}{{{2\pi ^2}R}}$
$\frac{{{\mu _0}I}}{{{2\pi }R}}$
$\frac{{{\mu _0}I}}{{{4\pi }R}}$
.......$A$ should be the current in a circular coil of radius $5\,cm$ to annul ${B_H} = 5 \times {10^{ - 5}}\,T$
A long, straight wire is turned into a loop of radius $10\,cm$ (see figure). If a current of $8\, A$ is passed through the loop, then the value of the magnetic field and its direction at the centre $C$ of the loop shall be close to
Due to $10\, ampere$ of current flowing in a circular coil of $10\, cm$ radius, the magnetic field produced at its centre is $3.14 \times {10^{ - 3}}\,Weber/{m^2}$. The number of turns in the coil will be
In the figure, find out the magnetic field at $B$ (Given $I =2.5 \;A,r =5\, cm )$
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