Application of Magnets

For Levitation 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.