Magnetism

What is the rule of magnetism?

Like poles repel and unlike poles attract.

Lines of force are three-dimensional, surrounding a bar magnet on all sides.

When opposite poles of a magnet are brought together, the lines of force join up and the magnets pull together.

When like poles of a magnet are brought together, the lines of force push away from each other and the magnets repel each other.


Source: http://www.sciencetech.technomuses.ca/english/schoolzone/Information_Magnetic.cfm#whatare

SIX things to know about magnets

Almost everyone knows these six basic facts about how magnets behave:

1. A magnet has two ends called poles, one of which is called a north pole or north-seeking pole, while the other is called a south pole or south-seeking pole.
2. The north pole of one magnet attracts the south pole of a second magnet, while the north pole of one magnet repels the other magnet's north pole. So we have the common saying: like poles repel, unlike poles attract.
3. A magnet creates an invisible area of magnetism all around it called a magnetic field.
4. The north pole of a magnet points roughly toward Earth's north pole and vice-versa. That's because Earth itself contains magnetic materials and behaves like a gigantic magnet.
5. If you cut a bar magnet in half, it's a bit like cutting an earthworm in half! You get two brand new, smaller magnets, each with its own north and south pole.
6. If you run a magnet a few times over an unmagnetized piece of a magnetic material (such as an iron nail), you can convert it into a magnet as well. This is called magnetization.

Source: http://www.explainthatstuff.com/magnetism.html


What is a magnet?
A magnet is an object made of certain materials which create a magnetic field.  Every magnet has at least one north pole and one south pole.  By convention, we say that the magnetic field lines leave the North end of a magnet and enter the South end of a magnet.  This is an example of a magnetic dipole ("di" means two, thus two poles).  If you take a bar magnet and break it into two pieces, each piece will again have a North pole and a South pole.  If you take one of those pieces and break it into two, each of the smaller pieces will have a North pole and a South pole.  No matter how small the pieces of the magnet become, each piece will have a North pole and a South pole.  It has not been shown to be possible to end up with a single North pole or a single South pole which is a monopole ("mono" means one or single, thus one pole).  http://encarta.msn.com/find/Concise.asp?ti=004AD000
History
The ancient Greeks and Chinese discovered that certain rare stones, called lodestones, were naturally magnetized.  These stones could attract small pieces of iron in a magical way, and were found to always point in the same direction when allowed to swing freely suspended by a piece of string.  The name comes from Magnesia, a district in Thessaly, Greece.  For more history, check http://www.newi.ac.uk/BUCKLEYC/magnet.htm
Several scientists from the 1600s to today have greatly increased our understanding of magnets and their properties.  Be sure to check:
http://www.worldwideschool.org/library/books/hst/biography/FaradayasaDiscoverer/toc.html
http://www.ee.umd.edu/~taylor/frame1.htm
http://www-istp.gsfc.nasa.gov/Education/whmfield.html


Source: http://www.coolmagnetman.com/magindex.htm