Unit 4

Magnetism and Electromagnetism

Magnetism has been studied for many years. Some metals in their natural state attract small pieces of iron. This property is called magnetism. Materials that have this ability are called natural magnets. The first magnets used were called lodestones. Now artificial magnets are made in many different strengths, sizes, and shapes. Magnetism is important because it is used in electric motors, generators, transformers, relays, and many other electric devices. The earth itself has a magnetic field like a large magnet.

Electromagnetism is magnetism that is brought about by electric current flow. Many electric machines operate because of electromagnetism. This unit deals with magnetism, electromagnetism, and some important ...

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