Question

Discuss Curie’s law for paramagnetic material. 

OR

State Curie’s law of paramagnetism.

Answer 1

Curie’s law : The magnetization of a paramagnetic material is directly proportional to the external magnetic field and inversely proportional to the absolute temperature of the material.

If a paramagnetic material at an absolute temperature T is placed in an external magnetic field of induction \(\vec {B_{ext}}\), the magnitude of its magnetization

M_z ∝ \(\cfrac{B_{ext}}T\)

∴ M_z = C \(\cfrac{B_{ext}}T\)

where the proportionality constant C is called the Curie constant.

[Notes : (1) The above law, discovered experimentally in 1895 by Pierre Curie (1859- 1906) French physicist, is true only for values of B_ext / T below about 0.5 tesla per kelvin.

(2) [C] = [M_z ∙ T] / [B_ext] = [L ^-1I∙^@ ] /[MT^-2 I^-1] = [M^-1L^-1T²I^2@],

where ^@ denotes the dimension of temperature.]