Electromagnets

In 1820, a scientist was working with electric currents. His name was Hans Christian Oersted. He discovered that when a current passed through a wire, a magnetic field was created. This led to the invention of electromagnets.

An electromagnet is made when a coil of wire is wrapped around something solid. The solid thing is called a core.

Electromagnets are only temporary magnets. That means they only work when there is an electric current going through the wire. When the electric current is turned off, the magnet no longer works.

Electromagnets are controlled because they can be turned on and off. People can also control how strong electromagnets are by adding or removing coils of wire. To make an electromagnet stronger, we add more coils of wire. The strength is also affected by the amount of electric current running through it. The more current an electromagnet has, the stronger it is.

Electromagnets are used in things like tape recorders, doorbells, burglar alarms, telephones, and some watches. They are also used to lift very large amounts of weight, like old cars.

The crane in this picture is using an electromagnet to pick up the car.
Picture used with permission from Microsoft Clipart.

To learn more about electromagnets, visit this web site:  http://www.factmonster.com/ce6/sci/A0816998.html

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