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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. Magnets come in different sizes and
shapes.
If a
magnet is brought close enough to another magnet, their fields will begin to
interact in the following ways:
· Like poles repel, unlike/opposite poles
attract.
Magnetic Field
You can see the magnetic
field of a bar magnet here shown by iron filings on a
piece of paper
Magnetic fields shown on a bar magnet and
the biggest magnet of all, Earth! Types of Magnets: Electromagnets
are used when really strong magnets are required. Electromagnets are produced
by placing a metal core inside a coil of wire carrying an electric current. The
electricity in the coil produces a magnetic field.
Electromagnets are
useful in cases where a magnet must be switched on or off; for instance,
large cranes to lift junked automobiles.
Maglev
trains use powerful magnets to hold a train just above the track and propel
it with little noise or vibration. In
an April time trial, a Japanese test Maglev set a speed record of 343 mph! Permanent
magnet
Lodestone
is a piece of magnetite that has magnetic properties and attracts iron or
steel. Temporary
magnets
Some things only become magnetic when a permanent
magnet is brought near it. These objects (nails, paper clips, staples, etc.)
are called temporary magnets. When the temporary magnet is removed from the field
of the permanent magnet, the temporary magnet is said to relax or loose its
magnetism Other
magnets:
A
compass is a magnet which can align itself within the Why do we
need magnets?
The discovery of magnets was
very important. They are used to make
electric motors and generators. Things that would disappear if we had no
electricity are telephones, lights, electric heat, computers, and
televisions. |
