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Magnets help us in a variety of ways.
We use them in computers, tape recorders, telephones, televisions, stereos,
cellular phones, VCR's, toasters, floppy disks, clocks, microwaves,
bathroom scales, and many more things. Without magnets you wouldn't
have those video game systems either.
There are a variety of stories claiming to explain the history of discovery
of magnetism. One involves a little Irish boy named Magnes and a piece
of “lodestone”. Another claims that more than two thousands
years ago the Greeks and Chinese were credited with discovering a material
that attracts iron. Since the material was discovered in a part of Turkey
called Magnesia, the Greeks called it Magnetite. Today any material
that attracts objects containing iron is called a “magnet”.
Magnets have an invisible force, by which they can attract or repel
other objects.
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All magnets have two
poles, exert forces, and are surrounded by a magnetic field. All
magnets have a north and a south pole. The force of repulsion or
attraction between magnetic fields is call the magnetic force. Moving
electrons within atoms can give the atoms a north and south pole.
When atoms in materials such as iron, nickel and cobalt line up
so that their north and south poles are aligned in the same direction,
the material exhibits a magnetic force. |
Magnets are made by pouring molten steel
into molds and then cooling it down in a strong magnetic field. After
cooling down and hardening the steel is magnetic
Danish physicist Hans Christian Oersted
discovered that an electric current produces a magnetic field. French
Scientist Andre-Marie Ampere heard about his discovery and did further
research. Electromagnetism is the interaction between electricity and
magnetism.
The links between electricity and magnetism makes possible electric
motors, electromagnets , and other useful devices, like those mentioned
above.
All magnets have a north and a south
pole at opposite ends.
Similar poles repel (push away from) each other, and opposite poles
attract (come together). Magnetic force is strongest at the poles.
There are 3 types of magnets: natural, temporary, and permanent. Natural
magnets, like lodestones, are naturally magnetic materials found on
Earth. Permanent magnets are made of 'hard' metal and hold their magnetism
for a long time. Temporary magnets are made of 'soft' metal and are
magnetic for a short time.
All magnets are made up of magnetic domains. These magnetic domains
are made up of atoms that align their north and south poles in the same
general directions. The more aligned domains within a magnet, the more
powerful that magnet is.
What are magnets used for? Basically they are used to hold, separate,
control, convey and elevate products and to convert electrical energy
into mechanical energy or convert mechanical energy into electrical
energy.
For a brief history of magnetism including an expanded
explanation of electromagnetism from lodestones to outer space visit:
http://search.britannica.com/frm_redir.jsp?query=magnetism&redir=http://www-spof.gsfc.nasa.gov/Education/Intro.html
Would
you like to see a frog made to fly using only a magnet?
http://www.sci.kun.nl/hfml/levitation-movies.html
How about how you can make a grape or watermelon react
to a magnet?
http://www.exploratorium.edu/snacks/diamagnetism_www/index.htm
Would you like to know how your electric doorbell works?
http://www.exploratorium.edu/snacks/magnetic_suction.html
What are some uses for magnets?
http://web.uvic.ca/educ/lfrancis/web/uses-for-magnets.html
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