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Hertz, Heinrich Rudolph

waves radio spark electric

(1857–94) German physicist: discovered radio waves.

Hertz studied at the universities of Munich and Berlin, at the latter under , whom he served as an assistant. In 1885 he was appointed professor of physics at Karlsruhe Technical College and later held a professorship at the University of Bonn.

Influenced by Helmholtz and by electromagnetic theory, he was the first to demonstrate the existence of radio waves, generated by an electric spark. In 1888 he showed that electromagnetic waves were emitted by the spark and could be detected by a tuned electric circuit up to 20 m away. Further experiments demonstrated that the waves, which had a wavelength of about a foot, could be reflected (from the laboratory walls), refracted (through a huge prism of pitch), polarized (by a wire mesh) and diffracted (by a screen with a hole in it) in the same way as light, and travelled at the same speed. This was an important verification of Maxwell’s ideas. Hertz also discovered in 1887 that an electric spark occurs more readily when the electrodes are irradiated with ultraviolet light (the Hertz effect), a consequence of the photoelectric effect. Hertz died at 36 (from blood poisoning) and did not live long enough to see turn radio transmission into a means of worldwide communication. The SI unit of frequency, the hertz (Hz, one cycle per second), is named in his honour.

Hertzsprung, Ejnar [next] [back] Hershko, Avram (1937–) - PERSONAL HISTORY, INFLUENCES AND CONTRIBUTIONS, BIOGRAPHICAL HIGHLIGHTS, PERSONAL CHRONOLOGY:, THE WORLD’S PERSPECTIVE, LEGACY

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