Paramagnetic Behavior and Curie's Law

Paramagnetic substances are characterized by their magnetic susceptibility ($\chi$) at temperatures above any ordering transition (like the ferromagnetic Curie temperature, $T_C$). Their behavior is typically described by the Curie's Law.

Curie's Law Explained

Curie's Law states that the magnetic susceptibility ($\chi$) of a paramagnetic material is inversely proportional to the absolute temperature ($T$) in Kelvin:

$ \chi = \frac{C}{T} $

Here, $C$ is the Curie constant, a material-specific positive constant.

Reciprocal Susceptibility vs. Temperature

To find the relationship for reciprocal susceptibility ($\frac{1}{\chi}$), we can rearrange Curie's Law:

$ \frac{1}{\chi} = \frac{T}{C} $

This equation shows a direct linear relationship between $\frac{1}{\chi}$ and $T$. The plot of $\frac{1}{\chi}$ versus $T$ should be a straight line.

Graphical Representation

• The equation $\frac{1}{\chi} = \frac{T}{C}$ represents a straight line passing through the origin (0,0), because when $T=0$, $\frac{1}{\chi}$ is also 0.
• The slope of this line is $\frac{1}{C}$, which is positive since $C$ is positive.
• Therefore, the correct plot is a straight line starting from the origin and extending with a positive slope as temperature increases.

The plot matching this description is shown in Option 3: