A magnet is an object or material that attracts certain metals, such as iron, nickel and cobalt. It can also attract or repel another magnet. All magnets have North-seeking (N) and South-seeking (S) poles. When magnets are placed near each other, opposite poles attract and like poles repel each other. Various electrical devices make use of magnets.
Types of magnets
There are permanent magnets, temporary magnets and electromagnets.
Permanent magnets
A permanent magnet is one that will hold its magnetic properties over a long period of time.
Magnetite
Magnetite is a magnetic material found in nature. It is a permanent magnet, but it is relatively weak.
Alloys
Most permanent magnets we use are manufactured and are a combination or alloy of iron, nickel and cobalt. Rare-earth permanent magnets are a special type of magnet that can have extreme strength.
Temporary magnets
A temporary magnet is one that will lose its magnetism. For example, soft iron can be made into a temporary magnet, but it will lose its magnetic power in a short while.
Electromagnet
By wrapping a wire around an iron or steel core and running an electrical current through the wire, you can magnetize the metal and make an electromagnet. If the core is soft iron, the magnetism will diminish as soon as the current is turned off. This feature makes electromagnets good for picking up and dropping objects. Typically DC electricity is used, but AC current will also result in an electromagnet.
2006-12-03 12:02:00
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answer #2
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answered by HK gal 5
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