Magnet
hideA 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 one made from a material that stays magnetized. An example is a 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 with an attraction strong enough to a magnet to be commonly considered "magnetic", all other substances respond weakly to a magnetic field, by one of several other types of magnetism.
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.
For more information about Magnet, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
News tagged with magnetic materials
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Scientists from Queen Mary, University of London have improved their understanding of the inner workings of our computers and mp3 players, thanks to an exciting new field of research called 'organic spintronics'.
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(PhysOrg.com) -- What do Saturn and flowers have in common? As shapes, both possess certain symmetries that are easily recognizable in the natural world. Now, at an extremely small level, researchers from ...
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A watery, mud-like substance has hit pay dirt for Case Western Reserve University engineering professor David Schiraldi and his research group.
Magnetism Governs Properties of Iron-Based Superconductors
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(PhysOrg.com) -- Though a year has passed since the discovery of a new family of high-temperature superconductors, a viable explanation for the iron-based materials’ unusual talent remains elusive. But a team ...
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Jan 28, 2009 |
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(PhysOrg.com) -- Researchers at the National Institute of Standards and Technology have discovered that a carefully built magnetic sandwich that interleaves layers of a magnetic alloy with a few nanometers ...
Nanotechnologists Gain Powerful New Materials Probe
Feb 25, 2009 |
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(PhysOrg.com) -- Researchers at the National Institute of Standards and Technology and The Johns Hopkins University have constructed a unique tool for exploring the properties of promising new materials with ...
Microswimmers" make a big splash for improved drug delivery
Jan 12, 2009 |
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They may never pose a challenge to Olympic superstar Michael Phelps, but the "microswimmers" developed by researchers in Spain and the United Kingdom could break a long-standing barrier to improving delivery of medications ...
