Following plots show Magnetization (M) vs Magnetising field (H) and Magnetic susceptibility ($$\chi$$) vs Temperature (T) graph:

Which of the following combination will be represented by a diamagnetic material?

Upon reviewing the physical definitions carefully, the previous derivation holds perfectly true, and the final solution is completely accurate. Let's do a quick structural review of the properties to reinforce why this is the correct answer:

Properties Review for Diamagnetic Materials

• Magnetization ($$M$$) vs. Magnetising Field ($$H$$): Since the magnetic susceptibility ($$\chi$$) of a diamagnetic material is a small negative constant, the relationship $$M = \chi H$$ yields a straight line with a negative slope passing through the origin. This corresponds perfectly to graph (a).
• Magnetic Susceptibility ($$\chi$$) vs. Temperature ($$T$$): Diamagnetism is an intrinsic orbital property of atomic electrons and is unaffected by thermal agitation. Therefore, $$\chi$$ is independent of temperature, which is represented by a horizontal line below the temperature axis. This corresponds perfectly to graph (c).

Conclusion

The solution requires no correction. The combination representing a diamagnetic material is indeed (a) and (c), which matches Option D