Question

If $\chi$stands for the magnetic susceptibility of a substance, $\mu$ for its magnetic permeability and ${\mu }_0$ for the permeability of free space, then

• A. For a paramagnetic substance: $\chi >0,\mu >0$
• B. For a paramagnetic substance: $\chi >0,\mu >{\mu }_0$
• C. For a diamagnetic substance: $\chi <0,\mu <0$
• D. For a ferromagnetic substance: $\chi >1,\mu >>{\mu }_0$

Answer 1

Answer: (B), (D)

The correct options are
B For a paramagnetic substance: $\chi >0,\mu >{\mu }_0$
D For a ferromagnetic substance: $\chi >1,\mu >>{\mu }_0$

$\chi ={\mu }_r-1,{\mu }_r=\frac{\mu }{{\mu }_0}$
For paramagnetic $\chi >0$ $\therefore$ ${\mu }_r>1$ $\therefore$ $\mu >{\mu }_0$
For diamagnetic $\chi <0$ $\therefore$ ${\mu }_r<1$ $\therefore$ $\mu <{\mu }_0$
for ferro magnetic $\chi >>1$ $\mu >>{\mu }_0$