Diamagnetism

Definition

Diamagnetism is a fundamental magnetic property of materials that arises from the orbital motion of electrons within atoms. It is a weak form of magnetism that occurs in all materials, but is typically overshadowed by stronger forms of magnetism such as paramagnetism and ferromagnetism.

5 Must Know Facts For Your Next Test

1. Diamagnetic materials are slightly repelled by magnetic fields, causing them to be weakly pushed out of the field.
2. Diamagnetism arises from the realignment of the orbital motion of electrons in atoms when placed in a magnetic field, creating a small magnetic field in the opposite direction.
3. Superconductors are perfect diamagnets, completely expelling magnetic fields from their interior, a phenomenon known as the Meissner effect.
4. Diamagnetism is a universal property of matter, but its effects are usually overshadowed by stronger forms of magnetism.
5. Diamagnetic materials have a relative magnetic permeability slightly less than 1 and a negative magnetic susceptibility.

Review Questions

• Explain how the orbital motion of electrons in atoms contributes to diamagnetism.
  • When a diamagnetic material is placed in an external magnetic field, the orbits of the electrons in the atoms of the material are slightly altered. This change in the electron orbits creates a small magnetic field within the material that opposes the external field, in accordance with Lenz's law. This induced magnetic field is the source of the diamagnetic effect, causing the material to be weakly repelled from the external magnetic field.
• Describe the relationship between diamagnetism and magnetic susceptibility.
  • Diamagnetic materials have a negative magnetic susceptibility, meaning they are slightly repelled by magnetic fields. The degree of diamagnetism, as measured by the magnetic susceptibility, is a fundamental property of the material and is related to the electronic structure of the atoms. Materials with a higher electron density, such as metals, tend to exhibit stronger diamagnetic effects due to the greater number of orbiting electrons that can interact with the external magnetic field.
• Analyze the role of diamagnetism in the Meissner effect observed in superconductors.
  • Superconductors are perfect diamagnets, meaning they completely expel magnetic fields from their interior. This phenomenon, known as the Meissner effect, is a direct consequence of the diamagnetic properties of superconductors. When a superconductor is placed in a magnetic field, the induced diamagnetic currents within the material create a magnetic field that perfectly cancels out the external field, resulting in the complete expulsion of the magnetic field from the superconductor's interior. This unique property of superconductors has important applications in technologies such as magnetic levitation and high-field magnets.

Related terms

Magnetic Susceptibility: A measure of the degree to which a material can be magnetized in an external magnetic field. Diamagnetic materials have a negative magnetic susceptibility.

Lenz's Law: A law that states the direction of the induced current in a conductor is such that it opposes the change in the magnetic field that caused it, in accordance with the principle of conservation of energy.

Eddy Currents: Electric currents that are induced in a conductive material when it is exposed to a changing magnetic field, creating a magnetic field that opposes the original change.