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Secret of Magnetism

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Research, p.1

Do you want to know a secret? First, consider this: When a magician performs a magic trick, many ask, "How did he do that?" Well...the true magician never tells because it is a secret. But when speaking about magnetism and its use in our everyday lives, you can learn the SECRET--the secret of magnetism! A true scientist would be glad to share his secrets through experimentation. Thus, I will share the secret with you. It begins with science--physics, to be exact: matter and energy, conduction and induction, magnetizing and demagnetizing. All will be explained in my science project. More importantly, to discover through experimentation that the secret behind magnetism could be its power! Let's start by defining an electromagnet.

An electromagnet is a temporary magnet formed when electric current flows through a wire or a conductor. Most electromagnets consist of wire wound around an iron core. This core is made from soft iron that loses its magnetism quickly when the electric current stops flowing through the wire.

Electromagnetism is the branch of physics that studies the relationship between electricity and magnetism. Electromagnetism is based on the fact that (1) an electric current or a charging electric field produces a magnetic field or (2) a charging magnetic field produces an electric field.

In 1820, the Danish scientist Hans Oersted discovered that a conductor carrying an electric current is surrounded by a magnetic field. When he brought a magnetized needle near a wire in which an electric current was flowing, the needle moved. Because a magnetized needle is moved by magnetic forces, the experiment proved that an electric current produces magnetism.

Research, p.2

Also, during the 1820's, the French physicist Andre' Marie Ampere declared that electric currents produce all magnetism. He concluded that a permanent bar magnet has tiny currents flowing in it. The work Oersted and Ampere did led to the development of the electromagnet--which is used in such devices as the telegraph and the electric bell. They confirmed as stated earlier: Most electromagnets consist of a coil of wire wound around an iron core. The electromagnet becomes temporarily magnetized when electric current flows through the wire. If the direction of the current changes, the poles of the electromagnet switch places.

Once again, the electrical current that flows through the wires produces a magnetic field. The magnet will only move if the magnetic field is strong enough. The wire carrying the electrical current behaves like a magnet. It either attracts or repels the magnet that is above it. If the direction of the magnetic field changes, then the direction of the electrical current changes. Magnetic field is formed in concentric circles around a current-carrying wire, laying the wire flat ensures that the strongest part of the wire's magnetic field interacts with the magnet. Electricity and magnetism cannot be separated. Remember, where there is an electric current, there is always a magnetic field!

Some examples where electromagnets are used in household items are: VCR's, tape players, television cameras, computer disk drives, many small motors and large motors and even doorbells--which we will learn about later in this project.

Electromagnets are also used in electric generators, to make trains move along the tracks, in junkyards via cranes to move automobiles and to separate metal trash for recycling.

Thus, to demonstrate on a smaller scale the power of electromagnets, I chose two experiments. First, I tested the strength of an electromagnet in three ways. The procedure demonstrated the following:

Research, p.3

The magnetic field strength produced by an electromagnet depends on the number of coils, the size of the current and how magnetic the core is. The more power supplied to the electromagnet, the stronger it will be. The number of coils also determines the strength of the field. The magnetic field around a single wire is quite weak, so coiling the wire around an iron core increases the strength of the electromagnet by concentrating on the magnetic field. Though wood, plastic and aluminum are not magnetic, there would still be some magnetic field, but not enough to attract any object.

Moving on to my second experiment, I learned more about electromagnets by making a doorbell. The electric doorbell



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