His mother was Anna Elisabeth Pfefferkorn.
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While studying at the
Gelehrtenschule des Johanneums in Hamburg, Hertz showed an aptitude for sciences as well as languages, learning
Arabic and
Sanskrit. He studied sciences and engineering in the German cities of
Dresden,
Munich and
Berlin, where he studied under
Gustav R. Kirchhoff and
Hermann von Helmholtz. In 1880, Hertz obtained his PhD from the
University of Berlin, and for the next three years remained for post-doctoral study under Helmholtz, serving as his assistant. In 1883, Hertz took a post as a lecturer in theoretical physics at the
University of Kiel. In 1885, Hertz became a full professor at the
University of Karlsruhe.
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In 1886, Hertz married Elisabeth Doll, the daughter of Max Doll, a lecturer in geometry at Karlsruhe. They had two daughters: Johanna, born on 20 October 1887 and
Mathilde, born on 14 January 1891, who went on to become a notable biologist. During this time Hertz conducted his landmark research into electromagnetic waves.
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Hertz took a position of Professor of Physics and Director of the Physics Institute in
Bonn on 3 April 1889, a position he held until his death. During this time he worked on theoretical mechanics with his work published in the book Die Prinzipien der Mechanik in neuem Zusammenhange dargestellt (The Principles of Mechanics Presented in a New Form), published posthumously in 1894.
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In 1864 Scottish mathematical physicist
James Clerk Maxwell proposed a comprehensive theory of electromagnetism, now called
Maxwell's equations. Maxwell's theory predicted that coupled
electric and
magnetic fields could travel through space as an "
electromagnetic wave". Maxwell proposed that light consisted of electromagnetic waves of short wavelength, but no one had been able to prove this, or generate or detect electromagnetic waves of other wavelengths.
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He used a
dipole antenna consisting of two collinear one-meter wires with a spark gap between their inner ends, and zinc spheres attached to the outer ends for
capacitance, as a radiator. The antenna was excited by pulses of high voltage of about 30
kilovolts applied between the two sides from a
Ruhmkorff coil. He received the waves with a resonant single-
loop antenna with a
micrometer spark gap between the ends. This experiment produced and received what are now called
radio waves in the
very high frequency range.
When an
induction coil applied a high voltage between the two sides, sparks across the spark gap created
standing waves of radio frequency current in the wires, which radiated
radio waves. The
frequency of the waves was roughly 50 MHz, about that used in modern television transmitters.]]
In the apparatus Hertz used, the electric and magnetic fields radiated away from the wires as
transverse waves. Hertz had positioned the
oscillator about 12 meters from a
zinc reflecting plate to produce
standing waves. Each wave was about 4 meters long.
citation needed Using the ring detector, he recorded how the wave's
magnitude and component direction varied. Hertz measured Maxwell's waves and demonstrated that the
velocity of these waves was equal to the velocity of light. The
electric field intensity,
polarization and
reflection of the waves were also measured by Hertz. These experiments established that light and these waves were both a form of electromagnetic radiation obeying the Maxwell equations. Hertz may not have been the first to come across the phenomenon of radio waves -
David Edward Hughes may have detected their existence nine years earlier but did not publish his findings.
citation needed
In 1892, Hertz began experimenting and demonstrated that
cathode rays could penetrate very thin metal foil (such as aluminium).
Philipp Lenard, a student of Heinrich Hertz, further researched this "
ray effect". He developed a version of the cathode tube and studied the penetration by X-rays of various materials. However, Lenard did not realize that he was producing X-rays. Hermann von Helmholtz formulated mathematical equations for X-rays. He postulated a dispersion theory before
Röntgen made his discovery and announcement. It was formed on the basis of the electromagnetic theory of light (Wiedmann's Annalen, Vol. XLVIII). However, he did not work with actual X-rays.
citation needed
Hertz helped establish the
photoelectric effect (which was later explained by
Albert Einstein) when he noticed that a
charged object loses its charge more readily when illuminated by
ultraviolet radiation (UV). In 1887, he made observations of the photoelectric effect and of the production and reception of electromagnetic (EM) waves, published in the journal
Annalen der Physik. His receiver consisted of a coil with a
spark gap, whereby a spark would be seen upon detection of EM waves. He placed the apparatus in a darkened box to see the spark better. He observed that the maximum spark length was reduced when in the box. A glass panel placed between the source of EM waves and the receiver absorbed UV that assisted the
electrons in jumping across the gap. When removed, the spark length would increase. He observed no decrease in spark length when he substituted quartz for glass, as
quartz does not absorb UV radiation. Hertz concluded his months of investigation and reported the results obtained. He did not further pursue investigation of this effect, nor did he make any attempt at explaining how the observed phenomenon was brought about.
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...on what was to become known as the field of
contact mechanics, which proved to be an important basis for later theories in the field.
Joseph Valentin Boussinesq published some critically important observations on Hertz's work, nevertheless establishing this work on contact mechanics to be of immense importance. His work basically summarises how two
axi-symmetric objects placed in contact will behave under
loading, he obtained results based upon the classical theory of
elasticity and
continuum mechanics. The most significant flaw of his theory was the neglect of any nature of
adhesion between the two solids, which proves to be important as the materials composing the solids start to assume high elasticity. It was natural to neglect adhesion at the time, however, as there were no experimental methods of testing for it.
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Hertz also described the "
Hertzian cone", a type of
fracture mode in brittle solids caused by the transmission of stress waves.
citation needed
Treatment by the Third Reich
His family was also persecuted for their non-Aryan status. Hertz's youngest daughter, Mathilde, lost a lectureship at Berlin University after the Nazis came to power and within a few years she, her sister, and their mother left Germany and settled in England.
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The section describes the Nazi regime as a political movement that "classified people by race instead of by religious affiliation"... Excuse me but why is the latter proposed as the alternative here? Wouldn't the alternative here be NOT classifying (implied to mean discriminating between) people based on any such component of identity, be it race or religion?
71.65.237.6 (
talk) 02:28, 27 November 2022 (UTC)
The SI unit
hertz (Hz) was established in his honor by the
International Electrotechnical Commission in 1930 for
frequency, an expression of the number of times that a repeated event occurs per second. It was adopted by the
CGPM (Conférence générale des poids et mesures) in 1960, officially replacing the previous name, "
cycles per second" (cps).
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In 1928 the
Heinrich-Hertz Institute for Oscillation Research was founded in Berlin. Today known as the Fraunhofer Institute for Telecommunications, Heinrich Hertz Institute, HHI.
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In 1980, in Italy a High School called "Istituto Tecnico Industriale Statale Heinrich Hertz" was founded in the neighborhood of Cinecittà Est, in Rome.
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The
Submillimeter Radio Telescope at Mt. Graham, Arizona, constructed in 1992 is named after him.
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A
crater that lies on the
far side of the
Moon, just behind the eastern limb, is
named in his honor. The Hertz market for radio electronics products in
Nizhny Novgorod, Russia, is named after him. The
Heinrich-Hertz-Turm radio telecommunication tower in Hamburg is named after the city's famous son.
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