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121 Hertz, Heinrich Rudolph
[br]b. 22 February 1857 Hamburg, Germanyd. 1 January 1894 Bonn, Germany[br]German physicist who was reputedly the first person to transmit and receive radio waves.[br]At the age of 17 Hertz entered the Gelehrtenschule of the Johaneums in Hamburg, but he left the following year to obtain practical experience for a year with a firm of engineers in Frankfurt am Main. He then spent six months at the Dresden Technical High School, followed by year of military service in Berlin. At this point he decided to switch from engineering to physics, and after a year in Munich he studied physics under Helmholtz at the University of Berlin, gaining his PhD with high honours in 1880. From 1883 to 1885 he was a privat-dozent at Kiel, during which time he studied the electromagnetic theory of James Clerk Maxwell. In 1885 he succeeded to the Chair in Physics at Karlsruhe Technical High School. There, in 1887, he constructed a rudimentary transmitter consisting of two 30 cm (12 in.) rods with metal balls separated by a 7.5 mm (0.3 in.) gap at the inner ends and metallic plates at the outer ends, the whole assembly being mounted at the focus of a large parabolic metal mirror and the two rods being connected to an induction coil. At the other side of his laboratory he placed a 70 cm (27½ in.) diameter wire loop with a similar air gap at the focus of a second metal mirror. When the induction coil was made to create a spark across the transmitter air gap, he found that a spark also occurred at the "receiver". By a series of experiments he was not only able to show that the invisible waves travelled in straight lines and were reflected by the parabolic mirrors, but also that the vibrations could be refracted like visible light and had a similar wavelength. By this first transmission and reception of radio waves he thus confirmed the theoretical predictions made by Maxwell some twenty years earlier. It was probably in his experiments with this apparatus in 1887 that Hertz also observed that the voltage at which a spark was able to jump a gap was significantly reduced by the presence of ultraviolet light. This so-called photoelectric effect was subsequently placed on a theoretical basis by Albert Einstein in 1905. In 1889 he became Professor of Physics at the University of Bonn, where he continued to investigate the nature of electric discharges in gases at low pressure until his death after a long and painful illness. In recognition of his measurement of radio and other waves, the international unit of frequency of an oscillatory wave, the cycle per second, is now universally known as the Hertz.[br]Principal Honours and DistinctionsRoyal Society Rumford Medal 1890.BibliographyMuch of Hertz's work, including his 1890 paper "On the fundamental equations of electrodynamics for bodies at rest", is recorded in three collections of his papers which are available in English translations by D.E.Jones et al., namely Electric Waves (1893), Miscellaneous Papers (1896) and Principles of Mechanics (1899).Further ReadingJ.G.O'Hara and W.Pricha, 1987, Hertz and the Maxwellians, London: Peter Peregrinus. J.Hertz, 1977, Heinrich Hertz, Memoirs, Letters and Diaries, San Francisco: San Francisco Press.R.Appleyard, 1930, Pioneers of Electrical Communication.See also: Heaviside, OliverKFBiographical history of technology > Hertz, Heinrich Rudolph
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122 Hertz pressure
< mech> (e.g. between tooth flanks, in roller bearings) ■ Hertz'sche Pressung f ; hertzsche Pressung f -
123 Hertz/Volt proportion
Korg, Yamaha <edp.av> ■ Hertz/Volt-Charakteristik f Korg, Yamaha ; Hz/V-Charakteristik f -
124 Hertz antenna
antena Hertz -
125 Hertz law
hukum Hertz -
126 Hertz oscillator
penalun Hertz -
127 Hertz principle of least curvature
asas lengkung terkecil HertzEnglish-Indonesian dictionary > Hertz principle of least curvature
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128 Hertz vector
vektor Hertz
См. также в других словарях:
hertz — HERTZ, hertzi, s.m. (fiz.) Unitate de măsură pentru frecvenţă, egală cu frecvenţa unei mişcări periodice a cărei perioadă este de o secundă; ciclu pe secundă. [pr.: herţ. – abr.: Hz] – Din germ. Hertz (n. pr.), fr. hertz. Trimis de gall,… … Dicționar Român
Hertz — steht für: Hertz (Einheit), die physikalische Einheit für die Frequenz The Hertz Corporation, das weltweit größte Automobilvermietungs Unternehmen Hertz (Familienname), einen Familiennamen Hertz (Band), eine Zürcher Band (16761) Hertz, ein… … Deutsch Wikipedia
hertz — [ ɛrts ] n. m. • 1930; du nom du physicien all. Hertz ♦ Métrol. Unité de mesure de fréquence d un phénomène périodique (symb.Hz). ⇒ kilohertz, mégahertz. hertz n. m. PHYS Unité de fréquence (symbole Hz). 1 Hz est la fréquence d un phénomène dont… … Encyclopédie Universelle
Hertz 87,9 — Hertz 87.9 CampusRadio für Bielefeld Logo Sendestart 6.12.2000 … Deutsch Wikipedia
HERTZ (H. R.) — HERTZ HEINRICH RUDOLPH (1857 1894) Physicien allemand (oncle de Gustav Hertz, lauréat du prix Nobel de physique en 1925) né à Hambourg et mort à Bonn. Heinrich Rudolph Hertz, après des études d’ingénieur, abandonne cette branche pour la physique … Encyclopédie Universelle
Hertz — Hertz, n. [from the German physicist Heinrich Hertz.] a unit of frequency equal to one cycle per second; it is abbreviated Hz. It is commonly used to specify the frequency of radio waves, and also the clock frequencies in digital computers. For… … The Collaborative International Dictionary of English
hertz — hèrtz s.m.inv. TS fis. unità di misura della frequenza, pari a un periodo al secondo (simb. Hz) {{line}} {{/line}} DATA: 1937. ETIMO: da Hertz, nome del fisico tedesco Heinrich Rudolf Hertz (1857 94) … Dizionario italiano
hertz — [hə:ts US hə:rts] n plural hertz written abbreviation Hz [Date: 1800 1900; Origin: Heinrich Hertz (1857 94), German scientist who worked on energy waves] a unit for measuring the ↑frequency of ↑sound waves … Dictionary of contemporary English
hertz — [hʉrts] n. pl. hertz [after HERTZ Heinrich Rudolf] the basic unit of frequency in the ST system, equal to one cycle per second: abbrev. Hz … English World dictionary
Hertz — Hertz, 1) Henrik, dän. Dichter, geb. 27. Aug. 1797 (1798) in Kopenhagen, gest. daselbst 25. Febr. 1870, wurde nach dem frühen Tode seiner Eltern von dem bekannten Großhändler Nathanson erzogen, wo seine früh erwachende Neigung zur Poesie und… … Meyers Großes Konversations-Lexikon
*hertz — ● hertz nom masculin (de H. Hertz, nom propre) Unité de fréquence (symbole Hz) équivalant à la fréquence d un phénomène périodique dont la période est 1 seconde … Encyclopédie Universelle
