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Why does a magnet lose its magnetism over time?
Tue Aug 2020ADMIN
Magnetism is one of the four basic forces of nature. It is produced by the movement of charged subatomic particles, especially electrons. These negatively charged particles are constantly spinning around the nucleus, while also spinning around their own axis. The official name of the latter is electron spin, which is an intrinsic property that mainly acts to generate attractive or repulsive force, which we call magnetism.
 
You may ask: In this way, every piece of matter in the world contains trillions of electrons, and every electron is a tiny magnet. Isn't there a magnet everywhere? But what we see is that many objects around us are not magnetic.
 
This is because most electrons cancel each other's magnetism. According to Pauli's principle of incompatibility, electrons in the same orbital shell have opposite spins, so they cancel each other's magnetism. In some elements, such as iron and cobalt, only half of the final valence layer is filled and contains unpaired electrons. Since there are no opposing electrons to neutralize them, these unpaired electrons collectively endow their respective atoms with magnetic power.
 
When forming a crystal, the magnetic moments of the atoms may or may not be aligned in the same direction, depending on the result of the smallest internal energy. The area where a single magnetic moment is parallel to each other is called a magnetic domain. These magnetic domains and the response of individual atoms to external magnetic fields form the basis for the classification of various magnetic materials. Under the action of an external magnetic field, when each magnetic field faces the same direction, an element or material begins to behave like a permanent magnet.
 
Unless its magnetic domains are precisely aligned, magnetic materials cannot be called true magnetic materials. Any change in the direction of a single magnetic domain may result in a loss of net magnetic strength. Many natural factors will cause these magnetic fields to randomize, but the most common and destructive one is overheating.

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