The History of Magnets & Electromagnets
Magnetism is a naturally occurring phenomenon in which one object attracts another. Man has been using magnetism in navigation for hundreds of years. The electromagnet then came after the discovery of electricity. Now we use magnets every day in electronics such as computers and even in credit and debit cards.
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Magnets
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Magnets have been around since the dawn of time; however, there is no documentation of the basic properties of magnetism until the time of the ancient Greeks, who first recognized amber's ability to attract lightweight objects such as feathers, as well as mentioned the lodestone that was capable of attracting iron. Lodestones are rocks with a high concentration of iron in them, causing them to give off a magnetic field. These are natural occurrences of magnetism.
Electromagnets
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Electromagnets are slightly different. While general magnets draw their ability from inherent natural characteristics, electromagnets become magnets only when an electrical current is passed through or around them. The strength of the magnetic field is directly proportional to the amount of current passed through the wires. Once the electrical current ceases, the magnetic field dissipates.
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The Compass
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The oldest use of magnetic forces is the compass, which is simply a piece of iron that will consistently point north thanks to its interaction with Earth's magnetic field. The first recorded use of compasses comes from the Chinese. In 1086 AD, Shen Kua, a Chinese astronomer and mathematician, discussed the use of compasses in navigation in his text, "Meng ch'i pi t'an" (Dream Pool Essays). One hundred years later, Alexander Neckam, an English monk, provides a similar account in his text, "Des utensilibus" (On Utensils). Without the compass, the world as we know it might look very different. The Americas might not have been discovered at all.
Birth of the Electromagnet
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The birth of the electromagnet is credited to two separate scientists, one for the initial discovery, another for explaining it. In 1820, Danish scientist Hans Christian Ørsted discovered by accident that electrical currents created magnetic fields. Unfortunately, unable to do so, he published his work without an explanation. French scientist Andre-Marie Ampere would be the one to explain the phenomena and demonstrate how the direction of the electrical current affected the behavior of attraction or repulsion in metals.
Other Important Names
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Beyond the earlier documenters of the compass and the men responsible for the discovery and creation of the electromagnet, one should know a few other names in connection with magnets.
Nikolai Tesla was a contemporary of Thomas Edison. He is the father of alternating current (AC) in electricity. Think about the AC adapter that comes with almost all electrical devices. He lends his name, Tesla, as the unit of measurement for magnetic fields.
Sir Isaac Newton is famously known for his work on gravity, inspired by the falling apple. In the study of magnetism, a Newton is the force exerted by a magnetic field.
Francis Bitter created the Bitter plate to solve the problem of magnetic fields giving off high heat, which tended to damage both the field and the magnet creating it. Bitter made his magnet out of stacked copper plates with holes drilled through them, allowing for water to be poured through the magnet and thus carry away the waste heat, keeping the magnet cool. This also allowed scientists to enlarge the electromagnets and the fields they produced.
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