![]() ![]() ![]() This early design had a problem: the electric current it produced consisted of a series of "spikes" or pulses of current separated by none at all, resulting in a low average power output. Wire windings can conveniently produce any voltage desired by changing the number of turns, so they have been a feature of all subsequent generator designs, requiring the invention of the commutator to produce direct current. Faraday and others found that higher, more useful voltages could be produced by winding multiple turns of wire into a coil. Later homopolar generators would solve this problem by using an array of magnets arranged around the disc perimeter to maintain a steady field effect in one current-flow direction.Īnother disadvantage was that the output voltage was very low, due to the single current path through the magnetic flux. This counterflow limited the power output to the pickup wires, and induced waste heating of the copper disc. While current was induced directly underneath the magnet, the current would circulate backwards in regions that were outside the influence of the magnetic field. ![]() This design was inefficient, due to self-cancelling counterflows of current in regions of the disk that were not under the influence of the magnetic field. This was not a dynamo in the current sense, because it did not use a commutator. He also built the first electromagnetic generator, called the Faraday disk, a type of homopolar generator, using a copper disc rotating between the poles of a horseshoe magnet. The principle, later called Faraday's law, is that an electromotive force is generated in an electrical conductor which encircles a varying magnetic flux. The operating principle of electromagnetic generators was discovered in the years 1831–1832 by Michael Faraday. The current flowed out through the sliding spring contact m (connected to B') through the external circuit, and back through B to the center of the disk through the axle When the disk was turned, this induced an electric current radially outward from the center toward the rim. The horseshoe-shaped magnet (A) created a magnetic field through the disk (D). The Faraday disk was the first electric generator. ![]()
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