Question

Paramagnetic materials have:

• A. Large negative susceptibility
• B. Infinite susceptibility
• C. Zero susceptibility
• D. Small positive susceptibility

Hint:

Susceptibility ($\chi$) ranges:
Diamagnetic: $-10^{-5} \le \chi < 0$
Paramagnetic: $0 < \chi \le 10^{-3}$
Ferromagnetic: $\chi \gg 1$ (up to $10^5$)

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
The question asks about the characteristic magnetic susceptibility ($\chi$) of paramagnetic materials.

Step 2: Key Formula or Approach:
Magnetic susceptibility ($\chi$) relates the magnetization ($M$) of a material to the applied magnetic field intensity ($H$):
\[ M = \chi H \]

Step 3: Detailed Explanation:

• Paramagnetism: Occurs in materials containing unpaired electrons, which possess permanent magnetic dipole moments. In the absence of an external field, these dipoles are randomly oriented due to thermal agitation, resulting in zero net magnetization.

• When an external field is applied, the dipoles align weakly parallel to the field, enhancing the local magnetic field. This positive alignment results in a positive susceptibility ($\chi > 0$).

• Because the thermal energy is much larger than the magnetic alignment energy at standard temperatures, this alignment is weak, making the value of susceptibility small (typically between $10^{-5}$ and $10^{-3}$).

• For comparison:
- Diamagnetic materials have small negative susceptibility ($\chi < 0$).
- Ferromagnetic materials have very large positive susceptibility.

Step 4: Final Answer:
Paramagnetic materials have small positive susceptibility.