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In ancient times men knew of a special kind of rock that could pull
other rocks of the same kind and pieces of iron toward themselves. Such
rocks were called lodestones. Today man uses the same force exerted by
electromagnets and permanent magnets to provide magnetic aide to trains
and more efficient power generators. This report will focus on the use
of magnets in the generation of electricity and magnetically aided
trains.
Magnetism is defined as the force exerted by a magnetic field. A
magnetic field is defined as the energy exerted by the magnet. It is
caused by the alignment of the domains (sub-atomic particles) of an
object. When the domains are lined up they produce magnetism. When the
domains are not lined up then they cause the object to be demagnetized
(having no magnetic power). Materials such as air, wood, copper, and
water do not respond to the power of magnets. We then ask "Why and how
is it possible to make a magnet out of copper." Good question, and
simple answer. Copper becomes magnetic when an electric current is run
through it while spiraled around a magnet. Thus it is called an
electromagnet. (Fig. 1)
Fig. 1 The following facts are to state the properties of magnetic
force: 1. If free to rotate, permanent magnets point approximately
north-south. 2. Similar poles repel, dissimilar poles attract. 3.
Permanent magnets only attract objects with domains. 4. Magnetic forces
act at a distance, moreover through nonmagnetic barriers. 5. Things
attracted to permanent magnets (other than permanent magnets) also
become temporary magnets. 6. A coil of wire with an electric current
flowing through it becomes an electromagnet. 7. Putting iron inside the
coil greatly increases the strength of an electromagnet. 8.Changing
magnetic fields induce electric currents in copper and other conductors.
Some people like to talk about animal magnetism as a metaphor. Most
people do not know that it actually exists. There are very weak
magnetic fields around Homo-sapiens. The field can be detected by the
Superconducting QUantum Interference Device (SQUID).
Magnets play a key role in the generation of electricity. Figure two
below illustrates magnets in a generator. In order to produce
electricity either the loop or the magnets must be rotated relative to
one another.
Fig. 2 The energy for this rotation can be provided by a variety of
sources. One source is water which can be converted to steam, and is
then used to drive turbines that operate generators. The energy to boil
the water and convert it to steam comes from burning coal, oil, or
natural gas, or from the heat released by controlled nuclear reactions.
Rotation of the turbines may be driven by the gravitational potential
energy stored in water held behind the dam of a hydroelectric plant, by
wind in wind turbines, or by the steam produced naturally within the
Earth. These alternate power sources need to be used more around the
world in order to conserve fossil fuel.
Another way to conserve is by using maglev (magnetic levitation). In
1966 British engineer Geoffrey Polgreen, promoted the use of hard
ferrites (large compounds of iron oxide) for a maglev system called
Magnarail (Livingston 96). He constructed a model from bricks of
ferrite permanent magnets 12ft long with a 28in platform 18in wide. He
proposed that the system should have 5 tons of cargo, or 50 people and,
5 tons of magnets, and should be altogether less expensive than a
traditional train. One of the thing that he left out is that what
happens if a screwdriver or a hammer gets discarded onto the track. An
incident like that could result in serious consequences.
The Japanese have superconducting magnets on the cars and copper
coils in the guideway. When the electromagnet is turned on then it
repels the magnets in the car. In 1977 test runs of the vehicle were
started on Kyushu (southern most island). The four mile track allowed
the ML-500 to make a world train speed record of 312mph. Other models
were built afterwards with varying modifications.
The United States also proposed a maglev system in the 1970s called
Magnaplane. It was designed by Henry Kolm and Richard Thornton at MIT.
A 1/25 model was made but funding was cut by congress. This new form of
transportation may arrive late due to "perpetual" congressional
gridlock.
The Germans also have their own magsusp (magnetic suspension), not
maglev, system called Transrapid. The bottoms of the cars are wrapped
around a T-shaped track, and attracted up to a 3/8 inch
servo-controlled gap. Propulsion is caused by the magnets similar to
Japan's MLs. The program began in 1969, and the latest prototype is the
Transrapid 07 (Fig. 4), which reached a top speed of 310mph only 11mph
under the Japanese MLU002N (Fig. 5).
Fig. 4 Transrapid expects to build a rail line linking Hamburg and
Berlin. The cost for the project is estimated at $6 billion (U.S.),
"two thirds of which will be provided by the government" (Livingston
96). On a 180-mile track the trains should reach speeds of over 250mph,
and cover the distance in less than a hour.
Fig.5 The "experiment" so to speak, displays the basic principle of
maglev. Materials used were 4 triangle magnets, 2 "doughnut" magnets
and a sharpened pencil. All of the triangle magnets are faced the same
way. The pencil is then sharpened and taped at the parts where the
magnets will be (enough so that the magnet won't slide off). The
doughnut magnets are then placed on the taped ends, with the doughnut
magnets' poles facing the same direction as the respective triangles'.
The pencil with magnets is then hovered over the triangle magnets with
the sharpened end of the pencil resting on the board.
This array displays the near frictionless environment that these
maglev and magsusp trains operate in. even though these trains use
electric power, the amount used is much less than that of electric
trains and other electric vehicles.
Using a maglev or magsusp system give the world a faster means of
transportation. Magnetic systems will help us to conserve electric
energy. In using magnetic systems we must also be careful not to
deplete the supply of permanent magnets like the depletion of fossil
fuels.
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