Editing Permeability (electromagnetism) (section)

== Diamagnetism ==
{{Main|Diamagnetism}}
''Diamagnetism'' is the property of an object which causes it to create a [[magnetic field]] in opposition of an externally applied magnetic field, thus causing a repulsive effect. Specifically, an external magnetic field alters the orbital velocity of electrons around their atom's nuclei, thus changing the [[magnetic dipole moment]] in the direction opposing the external field. Diamagnets are materials with a [[magnetic permeability]] less than ''μ''<sub>0</sub> (a relative permeability less than 1).

Consequently, diamagnetism is a form of [[magnetism]] that a substance exhibits only in the presence of an externally applied magnetic field. It is generally a quite weak effect in most materials, although [[superconductor]]s exhibit a strong effect.