The History of Magnets and Electromagents

The History of Magnets and Electromagents Magnets and electromagnets have many uses, every electric motor,

generator or transformer requires a magnetic field for it's operation.

With the exception of a few special types, all use electromagnets. The

magnets mounted on large cranes are used to lift heavy loads.

Magnetism makes the generator supplying the electricity to your home

work and the radio, telephone and most other electrical gadgets work.

The properties of Magnetism were known to the Greeks as early as 700

B.C. It was found that a certain type of ore had the power to attract

pieces of iron which were in it's vicinity. The discovery was made in

a province called Magnesia, and the ore was given the name Magnetite

after its place of discovery. The type of magnetite which exhibits

magnetic properties is commonly known as Lodestone. Any material which

exhibits these magnetic properties is called a Magnet.

The first uses of magnetism were recorded by the Chinese, who are

believed to have used suspended pieces of magnetite as compasses

nearly 2000 years ago. Compasses were also used by the European

navigators, but not until about 1200 A.D. Christopher Columbus was

interested in the properties of magnetic compasses, and he made some

important observations on the accuracy of compasses during his voyage

to America in 1492. However, the first true study of magnetic

properties was not attempted until 1600, when William Gilbert, an

English physician, published a report on his experiments with magnets.

A careful and through study of magnets and the...

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carry magnetic lines of force much more readily than air and certain

other materials. To increase the magnetic field of a coil, it is

common practice to insert a piece of iron through the center of the

coil. This piece of iron is called the core, and it's low reluctance

permits passage of many more magnetic lines of force through it than

the surrounding air will carry. It tends to concentrate the coil's

magnetic field.

The magnetic behavior of a coil carrying electric current can be

summed up in the following three statements:

Whenever current is present in a coil of wire, a magnetic field is set

up in and around the coil, which then exibits all of the properties of

a magnet.

The strength of the magnetic field varies with the number of turns and

the current. With no current, there is no magnetism.