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[العمييد]

term "paramagnetic" is the quality or the characteristic of a paramagnet. A paramagnet is a magnet made of a substance whose magnetisation is progressively proportional to the strength of the magnetic field applied to it. Para magnetism works only in the presence of an externally applied magnetic field. A paramagnetic material attracted to magnetic fields has a magnetic permeability which is greater than 1. However unlike ferromagnets (materials like iron, cobalt and nickel) which become magnetised in the presence of a magnetic field and preserve their magnetism even when the field is removed, paramagnetic materials do not retain any of the magnetisation in the absence of the external magnetic field. Some of the examples of paramagnetic materials are gaseous nitric oxide, organic free radicals, rare-earth etc.

Diamagnetism is a type of magnetism exhibited by certain materials that become magnetised in a magnetic field having a polarity which is contradictory to the magnetic force. Unlike ferromagnetic materials like iron, the diamagnetic materials are to some extent, repelled by a magnet. Some of the examples of diamagnetic materials are copper, bismuth, gold, mercury, antimony and sodium chloride. The diamagnetic materials are known to exhibit magnetism only with respect to an externally applied magnetic field. Diamagnetism is the consequence of changes in the orbital motion of electrons caused by the external magnetic field. The induced magnetic moment is negligible and in a direction opposite to

that of the applied field

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