| | rating principle of electromagnetic generators was discovered in t he years of 1831â€"1832 by Michael Faraday. The principle, later called Faraday's law, is that an electromotive forc bxe is generated in an electri cal conductor pbx which encircles a varying magnetic flux. He also built the first electromagnetic generator, called the Faraday dis k, a type o pbx f homopolar generator, using a copper disc rotating between the poles of a horseshoe m xagnet. I pbx t produced a sma xll DC voltage. This design was inefficient, due to self-cancelling counterflows of curren t in regions that were not under the influence of the magnetic field. While current was induced directly underneath the ma pbx net, the current would circ ulate backwards bx in regions that were outside the influence of the magnetic field. This counterflow limi xted the power out bxput to the pickup wires, and induced waste heating of the copper disc. Later homopolar g xenerators would solve this problem by using an array of magnets arranged around the disc per imeter to maintain a steady field effect i pbx n one current-flow direction. Another disadvantage bxwas that the output xvoltage was very low, due to the sing le current path through the magneti bxc flux. Experimenters found that using mult iple turns of wire in a coil could produce higher, more useful voltages. Since the o pbx utput voltage is proport xional to the number of turns, generators could be easily designed to produce any desired voltage by varying the number of turns. Wire windings beca bxme a basic feature of all s bxubsequ xent generator designs. Independently of Faraday, the Hu pbx ngarian Anyos Jedlik started experimenti ng in 1827 with the electromagnetic rotating devices which he called electrom agnetic self- pbx rotors. In the prototype of the single-pole electric starter (fini shed between 1852 and 1854) both the stationary and the revolving parts were el ectromagnetic. He also may have formu |
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