Karl Ferdinand Braun
The German physicist Ferdinand Braun (1850-1918) received the Nobel Prize in Physics for his work on wireless telegraphy.
Karl Ferdinand Braun was born in Fulda, Germany, on June 6, 1850, the son of Konrad and Franziska (Gohring) Braun. Upon graduation from his local gymnasium, he entered the University of Marburg, later completing his Ph.D. at the University of Berlin in 1872 with a dissertation on the vibrations of elastic rods and strings.
Braun's career began at the University of Würzburg in 1872, where he worked as assistant to George Hermann Quincke, the eminent German physicist and authority on elastic vibrations—of which light (electromagnetic radiation) was thought to be a species. Braun remained with Quincke two years, publishing in 1874 the results of his research on mineral metal sulfides. He discovered that these crystals would conduct electrical currents in one direction only. This finding was important in electrical research and in measuring another property of substances, electrical conductivity. However, there were no immediate practical applications, and not until the early 20th century was the phenomenon employed in crystal radio receivers.
Braun next took a lectureship at the St. Thomas Gymnasium in Leipzig, a post he also held for two years. Then, from 1876 to 1880 he was extraordinary professor at the University of Marburg, his alma mater. In 1880 his itinerant career took him outside of Germany, to the University of Strasbourg in France, where he remained for three years engaged in research, leaving in 1883; he returned again in 1895 as professor of physics and director of the physics institute. In the intervening years, however, he worked in Germany. For three years he was professor of physics at the Technical High School in Karlsruhe, and in the year he left (1885), he also married Amelie Bühler; they had two sons and two daughters. This must have domesticated him, for he remained at his next job, in Tübingen, for ten years, helping to found the Physical Institute there.
After 1890 Braun produced much of the work for which he was later to become famous. Here, his skill as an inventor combined with his grasp of theoretical principles to effect two significant technological achievements—the coupled transmitter and coupled receiver for improved wireless performance (1899 patent) and the cathode-ray oscilloscope (1897).
Braun was attracted to the study of wireless transmission by the question of why it was so difficult to increase the range of transmission to more than 15 kilometers. Though he expected to extend the range of transmission through a mere increase in the production of the transmitter's power, his experience with Hertz oscillators proved that any attempt to increase the power output by increasing the length of the spark gap would find a limit beyond which the power output would only decrease. Braun found his answer in the creation of a sparkless antenna circuit—power from the transmitter was magnetically coupled through the transformer effect to an antenna circuit rather than directly linking it to the power circuit. Related to this work and complementing it was his investigation of aspects of radiotelegraphy, including directional transmission of electromagnetic waves, work on crystal detectors, and use of radio transmissions as beacons for navigation. For these achievements Braun received with Guglielmo Marconi of Italy in 1909 a Nobel Prize for his contributions to wireless telegraphy.
Braun also introduced the first oscilloscope by the use of alternating voltage to shift an electron beam (as it was later understood) within a cathode tube. The trace remaining on the tube's surface corresponded to the amplitude and frequency of the alternating-current voltage. Braun then made use of a rotating mirror to graph the trace he had produced. This invention proved to be an essential instrument in subsequent electronic research.
Despite his great achievements—in fact because of them—Braun's final years were not happy ones. In early 1915, only a few months after the outbreak of World War I, he travelled to the United States to testify on behalf of the Telefunken Co. in litigation involving radio broadcasting. There he remained until the United States entered the war, when it became impossible for him to leave. Though he lived with his son Konrad in New York City, which must have provided some comfort, he was unable to pursue his scientific interests. Deprived of a laboratory, and with little independent means, he spent his last years in inactivity, dying in Brooklyn on April 20, 1918.
Biographical information on Braun can be gleaned from several sources. Most extensive is the Dictionary of Scientific Biography, vol. II, Charles Gillispie, editor (1973). Also helpful is Who's Who in Science: Antiquity to Present, 1st. ed., edited by Allen G. Debus (1968). There is Heathcote, Nobel Winners in Physics, 1901-1950 (1953), but it contains little information on Braun's life.
Kurylo, Friedrich, Ferdinand Braun, a life of the Nobel prizewinner and inventor of the cathode-ray oscilloscope, Cambridge, Mass.: MIT Press, 1981. □
(b. Fulda Germany, 6 June 1850; d. Brooklyn, New York, 20 June 1918)
Braun studied at the University of Marburg and received his doctorate from the University of Berlin in 1872 with a dissertation on the vibrations of elastic rods and strings. He later did work in thermodynamics, but his major accomplishments were in electricity. Braun began his career as assistant to Quincke at Würzburg and later held positions at leipzig, Marburg, Karlruhe, and Tübingen; during the short period that he spent at Tübingen he founded the Physical Institute. From 1880 to 1883 Braun was at Strasbourg, and he returned there permanently in 1895 to become professor of physics and director of the Physical Institude. He was called to the United states to testify in litigation involving radio broadcasting and then was detained when the United states entered World War I. He died in a Brooklyn hospital on 20 June 1918.
Although his contributions were all in the realm of pure science. In 1909 Braun shared the Nobel Prize in physics with Marconi for his practical contributions to wireless telegraphy. The work recognized by the Nobel committee was his fundamental modification of Marconi’s transmitting system. Braun was first drawn to the study of wireless transmission by the puzzle of why it was so difficult to increase the range of the transmitter over 15 kilometers. it seemed to Braun that the range should easily be increased by increasing the power of the transmitter. his study of Hertz oscillators indicated that the attempt to increase the power output by increasing the length of the spark gap eventually reached a limit at which the spark caused a decrease in output. The solution, Braun thought, was to produce a sparkless antenna circuit. The power from the transmitter was coupled magnetically to the antenna circuit by a transformer effect instead of having the antenna directly in the power circuit. The principle has been applied to all such transmissions, including radio, radar, and television. A patent was granted on this circuit in 1899. Braun also developed an antenna that directed the transmission of electric waves in one direction.
In 1874 Braun published th results of his research on mineral metal sulfides. He found that these crystals conducted electric currents in only one direction. This information was important in electrical research and in measuring another property of substances, the electrical conductivity, but Braun’s discovery did not have immediate practical application. In the early twentieth century the principle that Braun had discovered was employed in crystal radio receivers.
The first oscilloscope, or Braun tube, was introduced in 1897. In order to study high–frequency alternating currents Braun used the alternating voltage to move the electron beam within the cathode tube. The trace on the face of the cathode tube represented the amplitude and frequency of the alternating–current voltage. He then produced a graph of this trace by use of a rotating mirror. The Braun tube was a valuable laboratory instrument, and modifications of it are a basic device in electronic testing and research. The principle of the Braun tube, moving an electron beam by means of alternating voltage, is the principle on which all television tubes operate.
I. Original Works. Among Braun’s writings are “On the Conduction of Current Through Sulpho-Metals”, in Poggendorff’s Annalen, 102 (1874), 550, and Drahtlose Telegraphie durch Wasser und Luft(Leipzig, 1901). His Papers are listed in the Royal Society’s Catalogue of Scientific Papers, 1884–1900 (1914), pp.773–774, and in the International Catalogue of Scientific Literature (1902), p. 65; (1904) p. 74; (1907) pp. 83–84: (1908) p. 85: (1912) pp. 74–75: (1917) pp. 73–74.
II. Secondary Literature. These are no full– length biofraphies of Braun. He is best remembered by biographers for his Nobel Prize, although his most important work was in pure science. Some information is given in N. de v. Heathcote, Nobel Prize Winners in Physics 1901–1950 (New York, 1953), pp.81–86: and The Nobel Prize– Winners and the Nobel Foundation 1901–1937 (Zurich, 1938), pp. 52–53.
Harold I. Sharlin
Braun, Karl Ferdinand
Karl Ferdinand Braun (fĕr´dēnänt´ broun), 1850–1918, German physicist. Braun taught at the Univ. of Marburg, Strasbourg Univ., Karlsruhe's Technische Hochschule, and the Univ. of Tübingen before being named director of Physics institute at Strasbourg in 1895. He conducted researches in electricity (an electrometer and a cathode-ray tube bear his name) and the transmission of signals by radio waves (wireless telegraphy). For his pioneering work on wireless telegraphy he shared with Marconi the 1909 Nobel Prize in Physics.