Electric currents, as used in the first half of the nineteenth century, flowed from one point to another in one direction. That is the kind of current one gets from batteries, and it is direct current (dc). It is easier, in working with electric generators, however, to get a kind of current that goes first in one direction, then in the other, alternating very rapidly, with the current intensity rising and falling like a sine wave. This is alternating current (ac).
Alternating current didn't seem as useful as direct current, but then in 1883 a Croatian electrical engineer, Nikola Tesla (1856-1943), constructed an induction motor that could make use of alternating current to do useful work.
Edison had committed himself to direct current, and he fought the use of alternating current, but he lost out eventually.
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|Publication:||Asimov's Chronology of Science & Discovery, Updated ed.|
|Article Type:||Reference Source|
|Date:||Jan 1, 1994|
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