Editing Permeability (electromagnetism) (section)

== Paramagnetism ==
{{Main|Paramagnetism}}
''Paramagnetism'' is a form of [[magnetism]] which occurs only in the presence of an externally applied magnetic field. Paramagnetic materials are attracted to magnetic fields, hence  have a relative magnetic permeability greater than [[1 (number)|one]] (or, equivalently, a positive [[magnetic susceptibility]]).

The magnetic moment induced by the applied field is ''linear'' in the field strength, and it is rather ''weak''. It typically requires a sensitive analytical balance to detect the effect. Unlike [[ferromagnetism|ferromagnets]], paramagnets do not retain any magnetization in the absence of an externally applied magnetic field, because [[thermal motion]] causes the spins to become ''randomly oriented'' without it. Thus the total magnetization will drop to zero when the applied field is removed. Even in the presence of the field, there is only a small ''induced'' magnetization because only a small fraction of the spins will be oriented by the field. This fraction is proportional to the field strength and this explains the linear dependency. The attraction experienced by ferromagnets is non-linear and much stronger so that it is easily observed, for instance, in magnets on one's refrigerator.