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