Magnetism

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Magnetism is a class of physical phenomena that are mediated by magnetic fields. Electric currents and the magnetic moments of elementary particles give rise to a magnetic field, which acts on other currents and magnetic moments. The most familiar effects occur in ferromagnetic materials, which are strongly attracted by magnetic fields and can be magnetized to become permanent magnets, producing magnetic fields themselves.

Types of magnetism

Diamagnetism

It is the tendency of a material to oppose an applied magnetic field, and therefore, to be repelled by a magnetic field.

Paramagnetism

It is the tendency of certain materials to be weakly attracted by an externally applied magnetic field, and form internal, induced magnetic fields in the direction of the applied magnetic field.

Ferromagnetism

It is the tendency of certain materials to form permanent magnets. Every ferromagnetic material has its own individual temperature, called the Curie temperature, or Curie point, above which it loses its ferromagnetic properties. This is because the thermal tendency to disorder overwhelms the energy-lowering due to ferromagnetic order.

Elements such as iron, nickel, cobalt and a few lanthanides are ferromagnetic.

References

Relevant Sciencemadness threads