Question

Domain theory explains:

• A. diamagnetism
• B. paramagnetism
• C. ferromagnetism
• D. superconductivity

Hint:

Associate "domains" directly with "ferromagnetism". This theory is essential for understanding why a piece of iron can be a permanent magnet or be unmagnetized, and how hysteresis loops are formed.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Domain theory is a model used in physics to explain the magnetic behavior of certain materials.
Step 2: Detailed Explanation:
The domain theory was proposed by Pierre Weiss in 1906 to explain the properties of ferromagnetic materials. It postulates that these materials are composed of small regions called magnetic domains. Within each domain, the atomic magnetic moments are aligned parallel to each other due to strong exchange forces, resulting in a strong local magnetization. However, in an unmagnetized piece of material, the domains are oriented randomly, so their magnetic fields cancel each other out, and the net magnetization is zero.
When an external magnetic field is applied, the domains aligned with the field grow at the expense of others, and the domains can also rotate to align with the field, leading to a strong overall magnetization. This theory successfully explains phenomena unique to ferromagnetism, such as magnetic saturation, hysteresis, and the existence of the Curie temperature.
Diamagnetism and paramagnetism are explained by the behavior of individual atoms and do not involve domains. Superconductivity involves the Meissner effect and is explained by BCS theory.
Step 3: Final Answer:
Domain theory is the cornerstone for explaining the behavior of ferromagnetic materials.