Force between two unit pole strength placed at a distance of one metre is
$1 \,N$
$\frac{{{{10}^{ - 7}}}}{{4\pi }}\,N$
${10^{ - 7\,}}\,N$
$4\pi \times {10^{ - 7}}\,N$
When the $N-$pole of a bar magnet points towards the south and $S-$pole towards the north, the null points are at the
A short bar magnet with its north pole facing north forms a neutral point at $P$ in the horizontal plane. If the magnet is rotated by $90^o$ in the horizontal plane, the net magnetic induction at $P$ is (Horizontal component of earth’s magnetic field = ${B_H}$)
If a hole is made at the centre of a bar magnet, then its magnetic moment will
The magnetic moment of a magnet of length $10\, cm$ and pole strength $ 4.0\, Am$ will be......$A{m^2}$
The $ S.I.$ unit of magnetic permeability is