# Curie Constant

In physics, unlike other physical constants, the curie constant is a material dependent property. It expresses the relation between the magnetic susceptibility of a material to its temperature. Measured using K.A.T-1.m-1.

## Formula

In SI units the Curie constant can be expressed as

$C=\frac{\mu _{0}\mu _{B}^{2}}{3k_{B}}ng^{2}J(J+1)$

Where,

• C is the Curie constant.
• n is the number of magnetic atoms per unit volume.
• g is the g-factor.
• μB is the Bohr magneton.
• kB is the Boltzmann constant.
• J is the angular momentum quantum number.
• μ0 is the permeability of free space.

For the two-level system, the above equation can be reduced to

$C=\frac{1}{k_{B}}n\mu _{0}\mu ^{2}$

In Gaussian units, the Curie constant can be expressed as

$C=\frac{\mu _{B}^{2}}{3k_{B}}ng^{2}J(J+1)$

Where,

• C is the Curie constant.
• n is the number of magnetic atoms per unit volume.
• g is the g-factor.
• μB is the Bohr magneton.
• kB is the Boltzmann constant.
• J is the angular momentum quantum number.

For the two-level system, the above equation can be reduced to

$C=\frac{1}{k_{B}}n\mu ^{2}$

### Applications

The Curie constant is used in Curie law. Which states that for any magnetic field with the fixed value, the Magnetisation of the material is inversely proportional to the temperature. Mathematically given by-

$M=\frac{C}{T}B$

Where,

• M is the magnetisation of a material.
• B is the magnetic field.
• T is the temperature.
• C is the Curie constant.

Hope you have understood about Curie constant. How it is defined, its Units, Formula in SI system of Units and Gaussian units along with terms and its applications in physics, especially in Curie law.

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