State the direction of magnetic dipole moment (From $\mathrm{S}$ to $\mathrm{N}$ pole of magnet). and Write the unit of magnetic dipole moment.

A magnet of magnetic moment $M$  and pole strength $m$  is divided in two equal parts, then magnetic moment of each part will be

Assume the dipole model for earth’s magnetic field $\mathrm{B}$ which is given by

${{\rm{B}}_{\rm{v}}} = $ vertical component of magnetic field

$ = \frac{{{\mu _0}}}{{4\pi }}\frac{{2m\,\cos \theta }}{{{r^3}}}$

${{\rm{B}}_H} = $ Horizontal component of magnetic field

${{\rm{B}}_H} = \frac{{{\mu _0}}}{{4\pi }}\frac{{m\,\sin \theta }}{{{r^3}}}$

$\theta $ $= 90^{°}$ -latitude as measured from magnetic equator.

$(a)$ Find loci of points for which : $\left| {{\rm{\vec B}}} \right|$ is minimum;

The magnetism of magnet is due to

Write difference between electrostatic and magnetics :

The magnetic field to a small magnetic dipole of magnetic moment $M$, at distance $ r$  from the centre on the equatorial line is given by (in $M.K.S. $ system)