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What Is A Permanent Magnet?
Jul 28, 2018

The permanent magnet is made of a ferromagnetic material that is magnetized by a strong external magnetic field. After the external magnetic field is turned off, the hard magnetic material used can remain partially magnetized.

After experiencing a strong magnetic field, the magnetic moments of all the atoms in these materials are directed in the same direction. Therefore, a strong external magnetic field is generated.

A magnet that can maintain its magnetic properties for a long time is called a permanent magnet. Such as natural magnets (magnetite) and artificial magnets (aluminum-nickel-cobalt alloy). In addition to the permanent magnets in the magnets, there are also electromagnets that need to be energized to be magnetic. 

Permanent magnets are also called hard magnets, which are not easy to lose magnetism and are not easily magnetized. However, if the permanent magnet is heated above the Curie temperature or in an environment with a reverse high magnetic field strength, its magnetism will also decrease or disappear. Some magnets are brittle and may break at high temperatures. AlNiCo magnets have a maximum service temperature of over 540 °C (1,000 °F), samarium-cobalt magnets and ferrites are approximately 300 °C (570 °F), neodymium magnets and soft magnets are approximately 140 °C (280 °). F), but the actual value will still vary depending on the grain of the material.

The materials used as the magnetizer and the electromagnet are mostly soft magnets. The polarity of the permanent magnet does not change, and the polarity of the soft magnet changes with the polarity of the applied magnetic field. They all attract iron objects, and we call this property magnetic.