Question

If γ is the susceptibility and μr is the relative permeability of a ferromagnetic substance, then

• A. γ << 1
• B. μr << 1
• C. μr = 0
• D. γ >> 1

Answer 1

The Correct Option is D

The correct option is: (D): γ >> 1.

The susceptibility (γ) and the relative permeability (μr) are two important parameters that describe the behavior of a material in the presence of a magnetic field. The susceptibility indicates how easily a material can be magnetized in response to an applied magnetic field, while the relative permeability indicates how much the material can enhance the overall magnetic field within itself compared to the vacuum.

For a ferromagnetic substance, both the susceptibility and the relative permeability can be significantly higher than 1. This is due to the presence of spontaneous magnetization and strong alignment of atomic or molecular magnetic moments within the material. In a ferromagnetic material, the individual magnetic moments of atoms or molecules tend to align in the same direction, creating domains of strong magnetic alignment.

The statement "γ >> 1" implies that the susceptibility of the ferromagnetic substance is much greater than 1. This makes sense for ferromagnetic materials due to the following reasons:

Strong Magnetic Response: Ferromagnetic materials have a very strong response to an applied magnetic field, which leads to a large enhancement of their magnetic properties. This is a result of the strong alignment of magnetic moments within the material's domains.

Spontaneous Magnetization: Ferromagnetic materials can exhibit spontaneous magnetization, meaning they can become permanently magnetized even without an external magnetic field. This further contributes to a high susceptibility.

Hysteresis Loop: Ferromagnetic materials display hysteresis loops in their magnetization curves. This means that even after the external magnetic field is removed, the material retains some level of magnetization, again indicating a high susceptibility.

Saturation Magnetization: Ferromagnetic materials can achieve high levels of saturation magnetization, where nearly all magnetic moments are aligned with the external field. This corresponds to a large susceptibility value.

Applications: Ferromagnetic materials are used in applications like transformers, inductors, magnetic storage media, and electromagnets. These applications rely on the high magnetic response of ferromagnetic materials.

In summary, the statement "γ >> 1" is justified