Heinrich (Rudolf) Hertz - Biography

Physicist, born in Hamburg, N Germany. He studied under Kirchhoff and Helmholtz in Berlin, and became professor at Bonn in 1889. His main work was on electromagnetic waves (1887), and he was the first to broadcast and receive radio waves. The unit of frequency is named after him.

Heinrich Rudolf Hertz

"I do not think that the wireless waves I have discovered will have any practical application."
Born	February 22, 1857 Hamburg, Germany
Died	January 1, 1894 Bonn, Germany
Residence	Germany
Nationality	German
Field	Physicist and Electronic Engineer
Institution	University of Kiel University of Karlsruhe University of Bonn
Alma Mater	University of Munich University of Berlin
Doctoral Advisor	Hermann von Helmholtz
Known for	Electromagnetic radiation

Heinrich Rudolf Hertz (February 22, 1857 - January 1, 1894) was the German physicist and mechanician for whom the hertz, an SI unit, is named. In 1888, he was the first to demonstrate the existence of electromagnetic radiation by building an apparatus to produce UHF radio waves.

Biography

Early years

Hertz was born in Hamburg, Germany, to Gustav Ferdinand Hertz, whose father converted from Judaism to Lutheranism and married into a Lutheran family, and Anna Elisabeth Pfefferkorn, herself a Lutheran.

Meteorology

Hertz had always had a deep interest in meteorology probably derived from his contacts with Willhelm von Bezold (he was Hertz's professor in a laboratory course at the Munich Polytechnic in the summer of 1878). Hertz, however, did not contribute much to the field himself except for some early articles as an assistant to Helmholtz in Berlin, including research on the evaporation of liquids, a new kind of hygrometer, and a graphical means of determining the properties of moist air when subjected to adiabatic changes.

Electromagnetic research

Hertz helped establish the photoelectric effect (which was later explained by others) when he noticed that a charged object loses its charge more readily when illuminated by ultraviolet light. 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, whereupon a spark would be seen upon detection of EM waves. Hertz concluded his months of investigation and reported the results obtained.

Earlier in 1886, Hertz developed a dipole antenna. In 1887, Hertz experimented with radio waves in his laboratory. These actions followed Michelson's 1881 experiment (precursor to the 1887 Michelson-Morley experiment) which did not detect the existence of aether drift, Hertz altered the Maxwell's equations to take this view into account for electromagnetism. Hertz used a Ruhmkorff coil-driven spark gap and one meter wire pair as a radiator.

Through experimentation, he proved that transverse free space electromagnetic waves can travel over some distance. Hertz had positioned the oscillator about 12 meters from a zinc reflecting plate to produce standing waves. Hertz measured Maxwell's waves and demonstrated that the velocity of radio waves was equal to the velocity of light. The electric field intensity and polarity was also measured by Hertz.

The Hertzian cone was first described by Hertz as a type of wave-front propagation through various media. Hertz also found that radio waves could be transmitted through different types of materials, and were reflected by others. Hertz did not understand the practical importance of his experiments. He stated that,

"It's of no use whatsoever[...] this is just an experiment that proves Maestro Maxwell was right - we just have these mysterious electromagnetic waves that we cannot see with the naked eye. But they are there."

Asked about the ramifications of his discoveries, Hertz replied,

"Nothing, I guess."

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".

Death and afterwards

In 1892, a bone malignancy was diagnosed (after a bout of severe migraines) and Hertz underwent some operations to correct the illness. His nephew Gustav Ludwig Hertz was a Nobel Prize winner, and Gustav's son Carl Hellmuth Hertz invented medical ultrasonography.

The SI unit hertz (Hz) was established in his honor by the IEC in 1930 for frequency, a measurement of the number of times that a repeated event occurs per unit of time (also called "cycles per sec" (cps)). In 1969 (East Germany), there was cast a Heinrich Hertz memorial medal. The IEEE Heinrich Hertz Medal, established in 1987, is "for outstanding achievements in Hertzian waves [...] presented annually to an individual for achievements which are theoretical or experimental in nature". ISBN 0-307-33598-4 Buchwald, Jed Z., "The creation of scientific effects : Heinrich Hertz and electric waves". ISBN 0-911302-74-3 Lodge, Oliver, "The work of Hertz and his successors : being a description of signalling across space without wires by electric waves, "The Electrician" series. Bryant, John H., "Heinrich Hertz, the beginning of microwaves : discovery of electromagnetic waves and opening of the electromagnetic spectrum by Heinrich Hertz in the years 1886-1892". 1988 IEEE/MTT-S Hertz Centennial Celebration exhibition at the 1988 MTT-S International Microwave Symposium) Baird, Davis. Hertz, "On the energy balance of the Earth", American Journal of Physics, vol. Jenkins, "The Discovery of Radio Waves - 1888; Heinrich Rudolf Hertz (1847-1894)". Russell Naughton, "Heinrich Rudolph (alt: Rudolf) Hertz, Dr : 1857 - 1894". "Heinrich Rudolph Hertz (1857 - 1894)". Struan Robertson, "Heinrich Hertz (1857 - 1894)".