An electron moving in a circular orbit of radius $r$ makes $n$ rotations per second. The magnetic field produced at the centre has magnitude
$\;\frac{{{\mu _0}ne}}{{2\pi r}}$
zero
$\;\frac{{{\mu _0}{n^2}e}}{r}$
$\;\frac{{{\mu _0}ne}}{{2r}}$
A cylindrical cavity of diameter a exists inside a cylinder of diameter $2$a shown in the figure. Both the cylinder and the cavity are infinitely long. A uniform current density $J$ flows along the length. If the magnitude of the magnetic field at the point $P$ is given by $\frac{N}{12} \mu_0$ aJ, then the value of $N$ is :
Write formula of magnetic field for ${\rm{x}}\,{\rm{ > }}\,{\rm{ > }}\,{\rm{R}}$.
A thin circular frame of radius $'a'$ is made of insulating material. A square loop is constructed with in it. If loop carrying current $I$ , then magnetic induction at geometrical centre $'O'$ will be
In the hydrogen atom, the electron is making $6.6 \times {10^{15}}\,r.p.s.$ If the radius of the orbit is $0.53 \times {10^{ - 10}}\,metre,$ then magnetic field produced at the centre of the orbit is......$Tesla$
Magnetic field at the centre $O$ of a square loop of side $'a'$ carrying current $I$ as shown in the figure is