Question

The relative permeability (\( \mu_r \)) of ferromagnetic substance is

• A. \( \mu_r<1 \)
• B. \( \mu_r = 1 \)
• C. \( \mu_r>1 \)
• D. \( \mu_r \gg 1 \)

Hint:

Ferromagnetic materials have relative permeability values much higher than 1, indicating their strong magnetic properties.

Answer 1

The Correct Option is D

Step 1: Definition of Relative Permeability.
The relative permeability (\( \mu_r \)) is the ratio of the permeability of a material to the permeability of free space (\( \mu_0 \)). It measures the ease with which a material can be magnetized.
Step 2: Characteristics of Ferromagnetic Substances.
Ferromagnetic substances, such as iron, cobalt, and nickel, have very high relative permeability (\( \mu_r \)), often much greater than 1. This allows them to be easily magnetized.
Step 3: Elimination of options.
- (A) \( \mu_r<1 \): Incorrect, this is characteristic of diamagnetic materials, not ferromagnetic materials.
- (B) \( \mu_r = 1 \): Incorrect, this is characteristic of non-magnetic materials like air and vacuum.
- (C) \( \mu_r>1 \): Incorrect, although ferromagnetic materials have a \( \mu_r>1 \), the correct answer is \( \mu_r \gg 1 \) (much greater than 1).
- (D) \( \mu_r \gg 1 \): Correct, ferromagnetic materials have much greater relative permeability, indicating a high ability to be magnetized.
Step 4: Conclusion.
Therefore, the relative permeability of ferromagnetic substances is much greater than 1.