Question

Paramagnetic materials behaves as diamagnetic materials :

• A. above Curie temperature
• B. below Curie temperature
• C. at normal temperature
• D. at very high temperature

Hint:

Remember that diamagnetism is a universal property of matter, present in all materials. In paramagnetic and ferromagnetic materials, it is simply masked by much stronger effects. The key here is the temperature dependence: paramagnetism is weakened by heat, while diamagnetism is not.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
All materials exhibit diamagnetism, a weak form of magnetism where an induced magnetic field opposes an external applied field. In paramagnetic materials, there is an additional magnetic effect due to the alignment of permanent atomic magnetic dipoles with the external field. The total magnetic susceptibility (\(\chi\)) is the sum of the paramagnetic (\(\chi_p\)) and diamagnetic (\(\chi_d\)) contributions: \(\chi = \chi_p + \chi_d\).
Step 2: Detailed Explanation:


Paramagnetic susceptibility (\(\chi_p\)) is positive and its magnitude is inversely proportional to the absolute temperature (T), according to Curie's Law (\(\chi_p \propto 1/T\)).
Diamagnetic susceptibility (\(\chi_d\)) is negative and largely independent of temperature.
For a paramagnetic material to behave as a diamagnetic material, its net susceptibility \(\chi\) must be negative. As the temperature (T) increases, the paramagnetic susceptibility (\(\chi_p\)) decreases and approaches zero at very high temperatures.
\[ \lim_{T \to \infty} \chi = \lim_{T \to \infty} (\chi_p + \chi_d) = 0 + \chi_d = \chi_d \]
Since \(\chi_d\) is negative, at very high temperatures, the positive paramagnetic contribution becomes negligible, and the material's magnetic response is dominated by its inherent weak diamagnetism. The Curie temperature is a concept related to ferromagnetic materials, not paramagnetic ones.
Step 3: Final Answer:
At very high temperatures, the paramagnetic effect diminishes, and the underlying diamagnetism becomes the dominant magnetic behavior.