Define pole strength of magnet. and Write the unit of pole strength of magnet
 

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

A bar magnet of magnetic moment $M$ is cut into two parts of equal length. The magnetic moment of each part will be ......... $M$

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;

Two bar magnets having same geometry with magnetic moments $M$ and $2 M$, are firstly placed in such a way that their similar poles are same side then its time period of oscillation is $T_{1}$. Now the polarity of one of the magnet is reversed then time period of oscillation is $T_{2},$ then

Each atom of an iron bar $(5\,cm \times 1\,cm \times 1\,cm)$ has a magnetic moment $1.8 \times {10^{ - 23}}\,A{m^2}.$ Knowing that the density of iron is $7.78 \times {10^3}\,k{g^{ - 3}}\,m,$ atomic weight is $56$ and Avogadro's number is $6.02 \times {10^{23}}$ the magnetic moment of bar in the state of magnetic saturation will be.....$A{m^2}$