In the figure, what is the magnetic field at the point $O$
$\frac{{{\mu _0}I}}{{4\pi r}}$
$\frac{{{\mu _0}I}}{{4\pi r}} + \frac{{{\mu _0}I}}{{2\pi r}}$
$\frac{{{\mu _0}I}}{{4r}} + \frac{{{\mu _0}I}}{{4\pi r}}$
$\frac{{{\mu _0}I}}{{4r}} - \frac{{{\mu _0}I}}{{4\pi r}}$
A straight wire carrying a current of $14\,A$ is bent into a semicircular are of radius $2.2\,cm$ as shown in the figure. The magnetic field produced by the current at the centre $(O)$ of the arc. is $.........\,\times 10^{-4}\, T$
Give convection for electric or magnetic field emerging out of the plane of the paper and going into the plane of paper.
A current of $0.1\, A$ circulates around a coil of $100$ $turns$ and having a radius equal to $5\, cm$. The magnetic field set up at the centre of the coil is $({\mu _0} = 4\pi \times {10^{ - 7}}\,weber/ampere - metre)$
A point charge $Q\left(=3 \times 10^{-12} C \right)$ rotates uniformly in a vertical circle of radius $R(=1 \,mm )$. The axis of the circle is aligned along the magnetic axis of the earth. At what value of the angular speed $\omega$, the eff ective magnetic field at the centre of the circle .............. $rad / s$ will be reduced to zero? (Horizontal component of earth's magnetic field is $30 \,\mu T )$
The fractional change in the magnetic field intensity at a distance $'r'$ from centre on the axis of current carrying coil of radius $'a'$ to the magnetic field intensity at the centre of the same coil is : (Take $r << a )$