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
Highlight: Biofunctionalized magnetic-vortex microdiscs
Nanotechnology / Nanomaterials
Dec 09, 2009 |
4.8 / 5 (4) |
0
Users from Argonne's Materials Science Division and University of Chicago's Pritzker School of Medicine, working collaboratively on a user science project with CNM's Nanobio Interfaces Group, have discovered ...
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Tiny nano-electromagnets turn a cloak of invisibility into a possibility
Dec 22, 2009 |
4.6 / 5 (15) |
9
A team of researchers at the FOM institute AMOLF (The Netherlands) has succeeded for the first time in powering an energy transfer between nano-electromagnets with the magnetic field of light.
Tiny magnetic discs could kill cancer cells: study
Nanotechnology / Bio & Medicine
Nov 29, 2009 |
3.8 / 5 (23) |
4
Tiny magnetic discs just a millionth of a metre in diameter could be used to used to kill cancer cells, according to a study published on Sunday.
Researchers create 'synthetic magnetic fields' for neutral atoms
Dec 02, 2009 |
4.9 / 5 (15) |
2
(PhysOrg.com) -- Achieving an important new capability in ultracold atomic gases, researchers at the Joint Quantum Institute, a collaboration of the National Institute of Standards and Technology and the University ...
Physicists see through the opaque with 'T-rays'
Dec 18, 2009 |
4.2 / 5 (11) |
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"T-rays" may make X-rays obsolete as a means of detecting bombs on terrorists or illegal drugs on traffickers, among other uses, contends a Texas A&M physicist who is helping lay the theoretical groundwork to make the concept ...
Researchers put a new spin on atomic musical chairs
Dec 02, 2009 |
5 / 5 (4) |
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Researchers from the National Institute of Standards and Technology and the Naval Research Laboratory have developed a new way to introduce magnetic impurities in a semiconductor crystal by prodding it with ...
Spinons -- confined like quarks
Nov 29, 2009 |
4.5 / 5 (16) |
2
The concept of confinement is one of the central ideas in modern physics. The most famous example is that of quarks which bind together to form protons and neutrons. Now Prof. Bella Lake from Helmholtz-Zentrum Berlin (Germany) ...
Super cool atom thermometer
Dec 07, 2009 |
5 / 5 (2) |
0
As physicists strive to cool atoms down to ever more frigid temperatures, they face the daunting task of developing new, reliable ways of measuring these extreme lows. Now a team of physicists has devised ...
Air Force Center of Excellence awarded in nanostructures and improved cognition
Nanotechnology / Nanomaterials
Dec 01, 2009 |
not rated yet |
0
The Georgia Institute of Technology has been awarded a U.S. Air Force Center of Excellence to design nanostructures for energy harvesting and adaptive materials, and to develop tools to optimize critical cognitive ...
A new kind of micro-mobility: Moving tiny particles using magnetic fields (w/ Video)
Dec 14, 2009 |
3.7 / 5 (3) |
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(PhysOrg.com) -- A new microscopic system devised by researchers in MIT's Department of Materials Science and Engineering could provide a novel method for moving tiny objects inside a microfluidic chip, and ...
Switchable Nanostructures Made with DNA
Nanotechnology / Bio & Medicine
Dec 21, 2009 |
4.6 / 5 (9) |
0
(PhysOrg.com) -- Scientists at the U.S. Department of Energy’s Brookhaven National Laboratory have found a new way to use a synthetic form of DNA to control the assembly of nanoparticles — this time resulting ...
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