Question

State and explain Curie’s law.

Answer 1

Hint: The curie’s law gives the magnetization of a paramagnetic material’s dependency upon the externally applied magnetic field and the temperature of the paramagnetic material. The formula of the Curie’s law is, $M=\dfrac{C.B}{T}$, where C refers to the curie’s constant.

Complete step by step answer:
To understand the curie’s law, we need to consider a paramagnetic material. In a paramagnetic material, the magnetization of the paramagnetic material is proportional to the externally applied magnetic field to the paramagnetic material. However, upon heating the paramagnetic material, the dependency on the field is reduced.
Under the heating condition, for a fixed value of the magnetic field applied to the paramagnetic material, the magnetization of the paramagnetic material is inversely proportional to the temperature of the paramagnetic material. This is known as the Curie’s law.
Hence, the Curie’s law can be formulated as: $M=\dfrac{C.B}{T}$, where C is known as the curie’s constant. The units of each of these are as follows:
M is the magnetization of the paramagnetic material, having the unit of Ampere per meter \[(A{{m}^{-1}})\]. B is the externally applied magnetic field to the paramagnetic material, having the unit of Tesla (T). T is the absolute temperature of the paramagnetic material, having the unit of Kelvin (K). C, the curie’s constant has the unit of Kelvin (K).
We must remember that the Curie’s law is only valid for high temperatures and weak magnetic fields. The magnetization saturates, when the temperatures are low or the applied external magnetic fields are strong.

Note: We must remember when a material, known as a paramagnetic material, to understand when the Curie’s law will be valid. The atomic magnetic moments of a paramagnetic material are random and the sum of all the atomic magnetic moments is zero. Hence, all the random atomic magnetic moments cancel each other under normal condition, that is under application of no external magnetic field. However, upon the application of the external magnetic field, the paramagnet gets converted into a magnetic material showing magnetic properties, since all the atomic magnetic moments get aligned along the external magnetic field’s direction.
Upon the removal of the external magnetic field, the magnetic properties go away making it back to a simple material, not showing any magnetic property.