$A$ permanent magnet:

The magnetic dipole moment of a short magnetic dipole at a distant point along the equator of the magnet has a magnitude of $X$ in $SI$ units. If the distance between the point and the magnet is halved,then the magnitude of the dipole moment will be

Write a brief history of magnets.

The incorrect statement regarding the lines of force of the magnetic field $B$ is:

The magnitude of magnetic fields at a distance $r$ from the centre of a short bar magnet,in longitudinal position to transverse position,is in the ratio:

Two like magnetic poles of strength $10$ and $40$ $SI$ units are separated by a distance of $30 \, cm$. The intensity of the magnetic field is zero on the line joining them at: