Question

If the magnetic dipole moment and susceptibility of an atom of diamagnetic material and paramagnetic materials are denoted by ${\mu }_d,{\mu }_p$ and ${\chi }_d,{\chi }_p$ respectively, then

• A. ${\mu }_d\ne 0,{\mu }_p\ne 0,{\chi }_d<0,{\chi }_p>0$
• B. ${\mu }_d=0,{\mu }_p\ne 0,{\chi }_d<0,{\chi }_p>0$
• C. ${\mu }_d\ne 0,{\mu }_p=0,{\chi }_d<0,{\chi }_p>0$
• D. ${\mu }_d=0,{\mu }_p\ne 0,{\chi }_d<0,{\chi }_p<0$

Answer 1

The correct option is B ${\mu }_d=0,{\mu }_p\ne 0,{\chi }_d<0,{\chi }_p>0$

$\text{Diamagnetic materials:}$
Diamagnetic materials have no net magnetic moment without the presence of an external applied magnetic field $\left(H\right)$.


However, as an external magnetic field is applied to a diamagnetic material, the spinning electrons experience a motion, producing electrical current and thus a magnetization $\left(M\right)$, which is in the opposite direction to that of the external magnetic field, as schematically shown in the figure.

Therefore, diamagnetic materials have a small negative magnetic susceptibility ${\chi }_d$.

Thus, ${\mu }_d=0$ and ${\chi }_d<0$

$\text{Paramagnetic materials:}$
The paramagnetic materials having unpaired electrons, whose spins do not cancel each other are called paramagnetic.
The magnetic moments of atoms are randomly orientated due to thermal agitation. When a magnetic field is applied, a few aligned magnetic moments produce a low magnetization in the direction of the field applied. So, the susceptibility of paramagnetic material is small and positive.

Thus, ${\mu }_p\ne 0$ and ${\chi }_p>0$

Hence, option $\left(D\right)$ is correct.