A bar magnet of magnetic moment $M$ is placed at right angles to a magnetic induction $B.$ If a force $F$ is experienced by each pole of the magnet, the length of the magnet will be

Write Gauss’s law for magnetism.

A short bar magnet of magnetic movement $5.25 \times 10^{-2} \;J\, T ^{-1}$ is placed with its axis perpendicular to the earth's field direction. At what distance from the centre of the magnet, the resultant field is inclined at $45^{\circ}$ with earth's field on

$(a)$ its normal bisector and

$(b)$ its axis.

Magnitude of the earth's field at the place is given to be $0.42 \;G$. Ignore the length of the magnet in comparison to the distances involved.

Many of the diagrams given in Figure show magnetic field lines (thick lines in the figure) wrongly. Point out what is wrong with them. Some of them may describe electrostatic field lines correctly. Point out which ones.

The magnetic lines of force inside a bar magnet