Define Remanence of a magnetic material. (AMIE, Mat Sc, Summer 2014, Remanence or remanent magnetization is the magnetization left behind in a ferromagnetic material (such as iron) after an external magnetic field is removed. It is also the measure of that magnetization. Colloquially, when a magnet is magnetized it has remanence. The remanence of magnetic materials provides the magnetic memory in magnetic storage devices, and is used as a source of information on the past Earths magnetic field in paleomagnetism. The equivalent term residual magnetization is generally used in engineering applications. In transformers, electric motors and generators a large residual magnetization is not desirable (see also electrical steel) as it is an unwanted contamination, for example a magnetization remaining in an electromagnet after the current in the coil is turned off. Where it is unwanted, it can be removed by degaussing. Sometimes the term retentivity is used for remanence measured in units of magnetic flux density.
Posted on: Wed, 02 Jul 2014 05:05:11 +0000
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