Question

The magnetic susceptibility is negative for

• A. Diamagnetic material only
• B. Paramagnetic material
• C. Ferromagnetic material
• D. Paramagnetic and ferromagnetic material

Answer 1

The correct option is A

Diamagnetic material only

Step 1 : Magnetic susceptibility :

1. It is a proportionality constant which determines the degree of magnetization of a material with respect to the applied magnetic field.
2. It is due to the interactions of electrons and nuclei with the applied magnetic field.
3. The magnetic susceptibility is the ratio of magnetization to the applied magnetizing field intensity.
4. The mathematical expression for it is $\mathrm{\chi }=\frac{\mathrm{M}}{\mathrm{H}}$, where $\chi$ = magnetic susceptibility, $\mathrm{M}$ = magnetization, $\mathrm{H}$ = field intensity.

Step 2 : Explanation for correct option :

1. Option $\left(\mathrm{A}\right)$ is correct option.
2. Diamagnetic material are the magnetic materials that align against the magnetic field.
3. The magnetic susceptibility of diamagnetic material is less than zero.
4. This means that a diamagnetic material always has a negative value of magnetic susceptibility.

Step 3 : Explanation for incorrect option :

1. Paramagnetic material are the magnetic materials that align with the magnetic field. The magnetic susceptibility of paramagnetic material is always greater than zero. Thus option $\left(\mathrm{B}\right)$ is incorrect.
2. Ferromagnetic material are the highly magnetized materials. Ferromagnetic material do not have constant permeability and they differ from 1000 to 100000. Thus option $\left(\mathrm{C}\right)$ is incorrect.
3. As both ferromagnetic and paramagnetic material have positive magnetic susceptibility. Hence option $\left(\mathrm{D}\right)$ is incorrect.