Question

Explain Curie's law for a paramagnetic substance.

Answer 1

Hint: Curie's law for a paramagnetic substance suggests that the magnetisation of the paramagnetic materials is dependent on mainly two factors. The magnetisation of the paramagnetic materials depends upon the external magnetic field applied and the temperature of the paramagnetic material.

Complete step-by-step answer:
Curie's law for a paramagnetic substance also gives a formula for the magnetisation of the paramagnetic materials, which is as follows
Magnetisation, $M = \dfrac{{CB}}{T}$,
where $C = $curie constant, $B = $external magnetic field and $T = $temperature of the paramagnetic substance.
This formula shows that magnetisation of a paramagnetic material is directly proportional to the external magnetic field, that is
$M \propto B$.
While the magnetisation is inversely proportional to the temperature of the material, that means the magnetisation of the Paramagnetic material will also be dependent on the extent of the temperature rise.
$M \propto \dfrac{1}{T}$.

Note: Here we have seen that the Curie’s law is applicable for the materials which are paramagnetic material. So, we have to understand what are the paramagnetic materials. Paramagnetic materials are the materials which get magnetised when placed in an external magnetic field. And also, there is a condition of placing the material in the magnetic field, that the material should be placed in the same direction as that of the applied external magnetic field. Some of the examples of the paramagnetic materials are oxygen, aluminium, iron oxide (FeO) and titanium. There are some other materials which are repelled by the external magnetic field because the applied external magnetic field induces the magnetic field in them in the opposite direction, causing the repulsive force in between. While the paramagnetic materials are attracted by a magnet.