Question

What is atomic model of magnetism? Differentiate between paramagnetic, diamagnetic, and ferromagnetic substances on this basis. Also, give one example of each. 
 

Hint:

Paramagnetic and ferromagnetic materials exhibit attraction to magnetic fields, while diamagnetic materials are repelled.

Answer 1

- Atomic Model of Magnetism: The atomic model of magnetism is based on the behavior of atomic magnetic moments, which arise from the motion of electrons (both orbital motion and spin). The magnetic properties of a material depend on how these magnetic moments align and interact. A material can exhibit different types of magnetism depending on the alignment of these moments. - Types of Magnetism:
1. Paramagnetic Substances:
- In paramagnetic materials, the magnetic moments of individual atoms tend to align with an external magnetic field but do not stay aligned when the external field is removed.
- These materials have a weak, positive susceptibility to magnetism.
- The atomic magnetic moments are typically not in alignment with each other due to thermal motion.
- Example: Aluminum. 2. Diamagnetic Substances:
- Diamagnetic materials do not have permanent atomic magnetic moments. When subjected to a magnetic field, they produce an opposing magnetic field and are repelled by the external field.
- These materials have a negative, weak susceptibility to magnetism.
- Example: Bismuth. 3. Ferromagnetic Substances:
- Ferromagnetic materials have permanent magnetic moments even without an external magnetic field. These magnetic moments can align to create a strong net magnetic moment, even without an external field.
- They exhibit strong positive magnetic susceptibility and can retain their magnetization even after the external magnetic field is removed.
- Example: Iron.