What is the term for the small amount of magnetism that remains in an item after the magnetic field is removed?

The term that refers to the small amount of magnetism that remains in an item after the magnetic field has been removed is known as "residual magnetism." This phenomenon occurs when certain materials, particularly ferromagnetic materials like iron, exhibit a certain level of magnetism even after the external magnetic influence has ceased.

Residual magnetism is significant because it indicates the material's ability to retain some of the magnetic characteristics imparted to it, which can be useful in applications like creating permanent magnets or understanding the magnetic properties of various materials.

Other concepts, such as induced magnetism, refer to the temporary magnetism that occurs while an external magnetic field is applied but does not persist once the field is removed. Permanent magnetism describes materials that maintain a constant magnetic field without needing an external magnetic source, while electromagnetic force pertains to the interaction between electrically charged particles and is not directly related to residual magnetism. Understanding these distinctions helps clarify the unique nature of residual magnetism in materials.