A D V E N T U R E S in C Y B E R S O U N DThomas Johann Seebeck : 1770 - 1831
Thomas Johann Seebeck was born in Tallin, Estonia, on 9 April 1770, into a wealthy merchant family. His father was German descent and perhaps because of this he encouraged Thomas to study medicine in Germany which he did at the Universities of Berlin and Gottingen. He received his medical degree in 1802, but since he preferred research in physics to the practice of medicine he went into education and research as a career. He is best known as a physicist. (1,2) After graduation he joined the faculty of the University of Jena where he met and became a good friend of Johann von Goethe. Inspired by the Romantic movement in Germany and the anti Newtonian theory of colors of Goethe he worked with Goethe on the theory of color and the effect of colored light. Seebeck then engaged in research of the solar spectrum. (1) He uncovered the effects of heating and chemicals on different colors of the solar spectrum in 1806. (2) In 1808, he obtained the first chemical combination of ammonia with mercuric oxide. (1) By 1812, he was studying optical polarization in stressed glass, but his discoveries in this area were discovered earlier, unknown to him, by scientists Brewster and Biot. (2) Seebeck returned to the University of Berlin around 1818 (3) as faculty where he worked independently on the magnetization of iron and steel when electrical currents were passed through conductors. The magnetic effects of electricity on iron and steel had just been discovered by Arago and Davy. (4) In early 1820, Seebeck searched experimentally for a relation between electricity and heat. In 1821, he joined two wires of dissimilar metals (copper wire and bismuth wire) to form a loop or circuit. Two junctions were formed by connecting the ends of the wires to each other. He then accidentally discovered that if he heated one junction to a high temperature, and the other junction remained at a cooler temperature a magnetic field was observed around the circuit of different temperatures. He did not recognize, believe, (2) or report that an electrical current was being generated when heat was applied to one junction of the two metals. He used the term thermomagnetic currents or thermomagnetism to express his discovery. (3) Seebeck is credited with the discovery of the thermoelectrical effect, but he used his discovery to incorrectly conclude that the earth's magnetic field was produced by the temperature differences between the two poles and the equator. (5) One might conjecture that electromagnetism had just recently been observed by Oersted, and that his discovery sort of fit into that model. He experimented with different metals, different structures (shapes) of the same metal and found the effects of electrical currents or, in his case deflections of his magnetic needle, when their junctions were heated. He even found that electrical currents flowed if one portion of a wire was hammered or twisted while the other portion of the same wire was not reshaped. Electrical current flowed continuously around the circuit created when two different metal wires were joined together by a soldered junction and then heated. This continuous flow of current with heat was different than that of voltaic current that he was so familiar with. The flow of current was formed at the soldered junction of the two metals whose temperatures differed at the soldered joint. (6) Seebeck published his findings about thermomagnetism in 1822-1823 as "Magnetische Plarisation der Matalle und Erze durch Temperatur-Differenz. Abhandlungen der Preussischen Akad, Wissenschaften, pp 265-373." (7) Experimenting further, he soldered a bar of antimony to a bar of bismuth and joined their ends. The magnetic needle deflected from bismuth to antimony when one soldered joint made by the two different metals was heated. The magnetic needle deflected in the opposite direction (antimony to bismuth) when the soldered joint was cooled. Later the observation was made that if metals were arranged according to their heating contrasts a series was formed: antimony, iron, zinc, silver, gold, lead, mercury, copper, platinum, and bismuth. The greater the heating contrasts between metals, the greater the electromotive force (EMF). Antimony and bismuth formed the best junction for EMF. (6) Seebeck also formed a circuit composed of copper and bismuth conductors (wires) in which he held one junction of the metals in one hand, and observed that the needle deflected from the difference in temperature of the metallic junctions caused by the heat of his hand. He experimented more by cooling one of the metallic junctions, and observed the same effect of an electrical current flowing in the circuit. (3) Dr Robert Hare, professor of chemistry at the University of Pennsylvania, Philadelphia, in 1822 had the English instrument maker Pepys construct a very large galvanic battery for him to use in electrical experiments. Dr Seebeck constructed a similar battery in 1823 independently of Pepys' battery for Hare. About the same time Dr Seebeck showed that the power of multiplication did not increase with the number of windings in the uniting wire of a coil. The resistance to current passage naturally increased with the length of the wire used, thus the conducting current is reduced rather than proportional to the number of windings as claimed by some at the time. Seebeck's observation was in response to Schweigger's newly constructed galvanometer. (8) In addition to the impact of thermoelectricity on theory, this effect is used in thermocouples to measure temperature. Seebeck's observation remained rather obscured for a hundred years until Shockley and associates invented the semiconductors. (9) Seebeck devised thermocouples; used thermoelements to measure temperature, built a polariscope (device to measure polarized light); studied heat radiation, and the rotary effect of sugar solutions on plane polarized light. Thomas Seebeck at the age of 61 years died in Berlin, Germany, on 10 December 1831. (1) He married and had at least one son, Louis Frederick. He became a member of the Berlin Academy of Sciences, and the French Academy of Sciences in 1825. (1) REFERENCES
The above essay was written and generously posted on this site by Dean P. Currier As 2000 progresses, other biographical studies by Dean Currier will also be added to this website. Thanks Dean.
Thomas Johann Seebeck was born in Reval (now Tallin), the capital of Estonia, that was then part of East Prussia. A member of a prominent merchant family with ancestral roots in Sweden, Seebeck studied medicine in Germany, qualifying as a doctor in 1802. Seebeck spent most of his life in scientific research. A contemporary of poet and scientist, Johann Wolfgang von Goethe (1749 - 1832) and philosopher, Georg Wilhelm Friedrich Hegel (1770 - 1831), the impact of these individuals on each other is reflected in their works although the relationship is rarely found discussed in English speaking journals. In 1821, Seebeck demonstrated the electrical potential in the juncture-points of two dissimilar metals when there is a heat difference between the joints. This was the thermoelectric effect and is known as the Seebeck Effect in Physics. It is the basis of the thermocouple and is considered the most accurate measurement of temperature. It is also a key component of the semi-conductor, the foundation
The Seebeck Effect The Seebeck effect, the work of Thomas Johann Seebeck (1770 - 1831), refers to the appearance of a thermo-emf in an electric circuit composed of heterogeneous conductors, which contacts have different temperatures. The conductors are connected in series. The temperature difference causes a flow of elctrons in the conductors, said flow being directed from the hot end to the cold one. In the point of the conductors' contact, a potential difference occurs. The magnitude of thermo-emf depends on the material of the conducts, contact temperature and does not depend on the temperature distribution along the conductors. The thermoelectric ability of the couple is evaluated by the Seebeck coefficient which lies for different materials with the range from +43 to -38 mcV/deg.
Thomas Johann Seebeck (b. Apr. 9, 1770, Tallinn, Estonia, Russian Empire--d. Dec. 10, 1831, Berlin, Prussia [Germany]), German physicist who discovered (1821) that an electric current flows between different conductive materials that are kept at different temperatures, known as the Seebeck effect. Seebeck studied medicine at Berlin and at the University of Gottingen, where he acquired an M.D. in 1802. However, he abandoned medical practice for scientific research. He was chosen (1814) as a member of the Berlin Academy and was awarded (1816) the academy's annual prize for his investigation of polarization in stressed glass. In numerous experiments on the magnetizability of various metals, he observed the anomalous reaction of magnetized red-hot iron, which eventually resulted in the phenomenon now known as hysteresis. Continued experiments with different metal pairs and a variety of conductors revealed that it was possible to place the many conducting materials in a thermoelectric series. His most important contribution, however, was the Seebeck effect. He discovered that if a copper strip was joined to a strip of bismuth to form a closed circuit, heating one junction induced a current of electricity to flow around the circuit as long as the difference in temperature existed. This remained true of any pair of metals, and his original experiment revealed that merely holding one junction by hand was adequate to produce a measurable current.
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