Step 1: Definition of Relative Permeability.
The relative permeability ( ) is the ratio of the permeability of a material to the permeability of free space ( ). 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 ( ), often much greater than 1. This allows them to be easily magnetized.
Step 3: Elimination of options.
- (A) : Incorrect, this is characteristic of diamagnetic materials, not ferromagnetic materials.
- (B) : Incorrect, this is characteristic of non-magnetic materials like air and vacuum.
- (C) : Incorrect, although ferromagnetic materials have a , the correct answer is (much greater than 1).
- (D) : 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.