## Diamagnetism – Class 12 | Chapter – 5 | Physics Short Notes Series PDF for NEET & JEE

Diamagnetism: Diamagnetism is one of the types of magnetic properties of materials. Diamagnetic materials are materials that are not attracted to a magnetic field, and their magnetization is in the opposite direction to the applied magnetic field. Diamagnetic materials have a weak, negative susceptibility, which means that the magnetic field induces a very small magnetization in the opposite direction to the applied magnetic field.

The origin of diamagnetism is due to the motion of electrons in the material. According to Lenz’s law, when an external magnetic field is applied to a diamagnetic material, the electrons move in such a way that they produce a magnetic field in the opposite direction to the applied magnetic field, which results in the material being repelled by the magnetic field. This effect is weak, and the magnetic moment produced by the electrons is generally small, which explains why diamagnetic materials are not strongly attracted to magnetic fields.

## Properties of Diamagnetism

Diamagnetism is a weak type of magnetism exhibited by materials that are not attracted to a magnetic field. Here are some properties of diamagnetism:

• Weak magnetic moment: Diamagnetic materials have a weak, negative susceptibility, which means that they produce a magnetic moment in the opposite direction to the applied magnetic field. This magnetic moment is generally very small, which explains why diamagnetic materials are not strongly attracted to magnetic fields.
• Opposite direction: The magnetic moment produced by the electrons in a diamagnetic material is in the opposite direction to the applied magnetic field, which results in the material being repelled by the magnetic field.
• Induced magnetism: Diamagnetic materials do not have a permanent magnetization, but they can be magnetized by an external magnetic field. However, this induced magnetism is weak and disappears when the external magnetic field is removed.
• Temperature dependence: The diamagnetic susceptibility of a material depends on the temperature. In general, the diamagnetic susceptibility of a material decreases with increasing temperature.
• Isotropic: The diamagnetic susceptibility of a material is isotropic, which means that it does not depend on the direction of the applied magnetic field.
• Occurrence: Diamagnetic behavior occurs in all materials to some degree, but it is generally overshadowed by other stronger magnetic properties.

## Examples of Diamagnetism

Diamagnetism is a weak type of magnetic property exhibited by materials that are not attracted to magnetic fields. Here are some examples of diamagnetic materials:

• Copper
• Silver
• Gold
• Carbon (in its graphite form)
• Bismuth
• Mercury
• Water
• Organic compounds such as benzene and toluene.

All of these materials exhibit weak, negative susceptibility and are repelled by magnetic fields. The degree of diamagnetism in these materials is generally very small, and as a result, the effect is often difficult to detect. However, the phenomenon of diamagnetism can be observed in some interesting ways, such as in the levitation of a superconductor above a magnet.

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