object that a field
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This article is about objects and devices that produce magnetic fields. For a description of magnetic materials, see magnetism. For other uses, see Magnet (disambiguation).
Iron filings that have oriented in the magnetic field produced by a bar magnet
Magnetic field lines of a solenoid which are similar to a bar magnet as illustrated above with the iron filingsA magnet (from Greek μαγνήτις λίθος magnḗtis líthos, "Magnesian stone") is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials and attracts or repels other magnets.
A permanent magnet is an object made from a material that is "magnetized" and creates its own persistent magnetic field. An example is a refrigerator magnet used to hold notes on a refrigerator door. Materials that can be magnetized, which are also the ones that are strongly attracted to a magnet, are called ferromagnetic (or ferrimagnetic). These include iron, nickel, cobalt, some rare earth metals and some of their alloys (e.g. Alnico), and some naturally occurring minerals such as lodestone. Although ferromagnetic (and ferrimagnetic) materials are the only ones attracted to a magnet strongly enough to be commonly considered "magnetic", all other substances respond weakly to a magnetic field, by one of several other types of magnetism.
Some ferromagnetic materials can be magnetised by a magnetic field but do not tend to remain magnetised when the field is removed; these are termed soft. Permanent magnets are made from magnetically hard ferromagnetic materials that stay magnetized. permanentmagnets net/
An electromagnet is made from a coil of wire which acts as a magnet when an electric current passes through it, but stops being a magnet when the current stops. Often an electromagnet is wrapped around a core of ferromagnetic material like steel, which enhances the magnetic field produced by the coil.
The overall strength of a magnet is measured by its magnetic moment, while the local strength of the magnetism in a material is measured by its magnetization.
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