The Science and Use of Magnets (Electromagnets)

Gtech 2018-03-25

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We played with them as children, but the world of magnets isn't kid's stuff! The pervasive magnet serves as the underpinning for much of modern technology. They can be found in computers, cars, phones, VCRs, TVs, vacuum cleaners, the washer and dryer, the ubiquitous refrigerator magnet, and even in an electric guitar! On the cutting edge of technology, scientists experiment with a variety of magnets. Magnets' amazing forces of attraction and repulsion may some day take us to the far reaches of outer space. This film reveals the essential role magnets play in today's society - from powering high-speed trains and theme-park rides to generating electricity and creating mechanical power, and also providing the basis for computers and data storage.
Ancient people learned about magnetism from lodestones, which are naturally magnetized pieces of iron ore. The word magnet was adopted in Middle English from Latin magnetum "lodestone", ultimately from Greek μαγνῆτις [λίθος] (magnētis [lithos]) meaning "[stone] from Magnesia", a part of ancient Greece where lodestones were found. Lodestones, suspended so they could turn, were the first magnetic compasses. The earliest known surviving descriptions of magnets and their properties are from Greece, India, and China around 2500 years ago. The properties of lodestones and their affinity for iron were written of by Pliny the Elder in his encyclopedia Naturalis Historia.

By the 12th to 13th centuries AD, magnetic compasses were used in navigation in China, Europe, the Arabian Peninsula and elsewhere

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