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| Heinrich Rudolph Hertz (1857 - 1894)
In 1887 Hertz tested Maxwell's hypothesis. He used an oscillator made of polished brass knobs, each connected to an induction coil and separated by a tiny gap over which sparks could leap. Hertz reasoned that, if Maxwell's predictions were correct, electromagnetic waves would be transmitted during each series of sparks. To confirm this, Hertz made a simple receiver of looped wire. At the ends of the loop were small knobs separated by a tiny gap. The receiver was placed several yards from the oscillator. According to theory, if electromagnetic waves were spreading from the oscillator sparks, they would induce a current in the loop that would send sparks across the gap. This occurred when Hertz turned on the oscillator, producing the first transmission and reception of electromagnetic waves. Hertz also noted that electrical conductors reflect the waves and that they can be focused by concave reflectors. He found that nonconductors allow most of the waves to pass through. Another of his discoveries was the photoelectric effect. In 1889 Hertz was appointed professor of physics at the University of Bonn. (reference) Hertz opened the way for the development of radio, television, and radar with his discovery of electromagnetic waves between 1886 and 1888. James Clerk Maxwell had predicted such waves in 1864. Hertz used a rapidly oscillating electric spark to produce waves of ultrahigh frequency. He showed that these waves caused similar electrical oscillations in a distant wire loop. He also showed that light waves and electromagnetic waves were identical (see Electromagnetism). Hertz was born in Hamburg. Other biographies: Aldini, Ampère, Arrhenius, Avogadro, Bacon, Berzelius, Boltzmann, Boyle, Bunsen, Callan, Carnot, Cavendish, Coulomb, Daniell, Davy, Debye, Dillon, Dow, Edison, Einstein, Evans, Faraday, Fick, Fontana, Franklin, Galvani, Gauss, Gibbs, Gilbert, Grove, Guericke, Hall, Helmholtz, Héroult, Hertz, Hoar, Joule, LaQue, Leclanché, Mendeleev, Millikan, Musschenbroek, Nernst, Newton, Ohm, Ørsted, Parkins, Planté, Poisson, Pourbaix, Reynolds, Ritter, Speller, Stokes, Tesla, Thomson, Uhlig, Volta, Watt, Weston
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