Magnetic materials are classified into three categories, based on the behaviour of materials in the magnetic field. The three types of materials are diamagnetic, paramagnetic and ferromagnetic.
Diamagnetic substances when placed in an external magnetic field produce negative magnetization. Therefore, diamagnetic substances are repelled by magnets. Paramagnetic substances acquire a small net magnetic moment in the direction of the applied field. Therefore, they are slightly attracted by the magnetic field.
Ferromagnetic materials are strongly attracted by the magnetic field. These materials retain the magnetism even when the magnetic field is removed. This lagging of magnetization of a ferromagnetic substance behind the magnetic field is called Hysteresis.
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