Question

If the susceptibility of dia, para and ferro magnetic materials are ${X_d}$,${X_p}$and ${X_f}$ respectively, then
(A) ${X_d}$<${X_p}$<${X_f}$
(B) ${X_f}$<${X_p}$<${X_d}$
(C) ${X_f}$<${X_d}$<${X_p}$
(D) ${X_d}$<${X_f}$<${X_p}$

Answer 1

Magnetic susceptibility is measure of how much a material can be magnetized in the presence of an external magnetic field. The materials are classified as dia, para and ferro based on this measure.

Complete solution: Diamagnetic materials are typically characterized by their weak response to the magnetic field as their magnetic susceptibility is low and negative. These materials are typically non-magnetic.
The paramagnetic materials respond better than the diamagnetic material under the presence of an external field and they have small and positive susceptibility to the magnetic fields.
The ferro-magnetic materials interact with magnetic fields between the dia and paramagnetic materials. Due to this they have very high positive magnetic susceptibility. Comparing the dia and paramagnetic material in order, if the magnetic susceptibility of dia, para and ferromagnetic material are given as${X_d}$,${X_p}$and ${X_f}$, then following is the relation between them:
${X_d}$<${X_p}$<${X_f}$

Hence the correct option is A.

Note: Typically of the three namely dia, para and ferro materials, the ferro materials retain their magnetization even after the external magnetic field is removed. Though the paramagnetic material responds to the external field, they don’t retain the magnetic effect compared to ferrous material. The nature of response of the material to the magnetic fields is more intrinsic to the nature of electrons and their interactions. The response is quantified using the magnetic susceptibility that involves the magnetic moment per unit to the intensity of the magnetic field, where the intensity of the magnetic field is related to the strength of the field. Since the magnetic susceptibility is determined by the characteristic of an atom, it can be used to understand the atomic bonding. An important aspect of magnetic susceptibility is its dependence on temperature especially for the para and ferromagnetic materials. The increase in temperature usually results in a loss of magnetic property of material due to thermal agitation. Curie temperature is the one when the material loses the magnetic property.