Gustav Kirchhoff

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Gustav Robert Kirchhoff

Library of Congress

[b. Königsberg (Kaliningrad, Russia), March 12, 1824, d. Berlin, October 17, 1887]

In 1845 Kirchhoff developed the laws governing current and resistance in electrical networks. In 1859 Kirchhoff and Robert Bunsen invented the spectroscope, obtaining spectrums from glowing samples. Kirchhoff recognized that elements can be identified this way and that dark lines in a star's spectrum represent elements in gas surrounding the star. He calculated the type of radiation to be emitted by a heated black body. Resolving contradictions between Kirchhoff's black-body theory and experiment led to the development of quantum theory.

The German physicist Gustav Robert Kirchhoff (1824-1887) is best remembered for his pioneeringwork in spectroscopy that permitted investigation of the chemical composition of stars.

Gustav Kirchhoff was born on March 12, 1824, in Königsberg, East Prussia, the son of a lawyer. He attended the local gymnasium and entered the University of Königsberg at the age of 18. Among his teachers were Franz Neumann, the noted theoretical physicist, and Friedrich Richelot, the mathematician. Shortly after he received his doctorate in 1847, he married Richelot's daughter, Clara; they had two sons and two daughters. Also in 1847, he received a rarely awarded travel grant from the university for a study trip to Paris, but the political situation forced him to cancel the plans. In 1848 Kirchhoff became privatdozent in Berlin, and 2 years later he obtained the post of extraordinary (associate) professor at Breslau. It was there that he first met Robert Bunsen. By 1854 both Kirchhoff and Bunsen were working together in Heidelberg.

The investigation of spectra with prisms had been going on for decades. There had also been several guesses made as to the identity between some lines in the solar spectrum and in spectra produced in laboratories. But it was Kirchhoff who, one afternoon in the summer of 1859, looked at the interaction of sunlight and the light of table salt burning in the flame of the Bunsen burner and said, "There must be a fundamental story here." When he returned to the laboratory the next day, he had the solution to his observation. It is known as Kirchhoff's law of radiation: the relation between the powers of emission and the powers of absorption for rays of the same wavelength is constant for all bodies at the same temperature. This law also implies that the bodies absorb more readily the radiation of such wavelengths as they tend to emit. Furthermore, the law implies that the greater the opacity of a body, the more complete its spectrum, and that the true emission spectrum of a substance is obtained in its gaseous state. Kirchhoff's now famous paper, written with Bunsen and published in 1859, also stated that "the dark lines [Fraunhofer lines] of the solar spectrum which are not caused by the terrestrial atmosphere, arise from the presence in the glowing solar atmosphere of those substances which in a flame produce bright lines in the same position."

Kirchhoff and Bunsen became celebrities overnight. Subsequent scientific developments did full justice to the elation of the moment. Spectroscopy turned out to be the magic key to a great number of practical discoveries, and half a century later it ushered in the era of modern atomic physics. In a sense, Kirchhoff's great success in spectroscopy drew attention away from his varied contributions to every branch of physics. He occupied the chair of theoretical physics at the University of Berlin from 1875 until his death on Oct. 17, 1887.

Further Reading

A short but informative account of Kirchhoff's life and work was written by Robert von Helmholtz and is available in English in the Smithsonian Institution Report (1889). The first two chapters of Edward Charles Cyril Baly, Spectroscopy (1905; 3d ed. 1927), contain much useful information on the origins and further developments of classical spectroscopy.

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Gustav Robert Kirchhoff
Gustav Kirchhoff
Born	12 March 1824(1824-03-12) Königsberg, East Prussia
Died	17 October 1887 (aged 63) Berlin, Germany
Residence	Germany
Nationality	German
Fields	Physicist
Institutions	University of Berlin University of Breslau University of Heidelberg
Alma mater	University of Königsberg
Doctoral advisor	Franz Ernst Neumann
Doctoral students	Max Noether Ernst Schröder
Known for	Kirchhoff's circuit laws Kirchhoff's law of thermal radiation Kirchhoff's laws of spectroscopy
Notable awards	Rumford medal

Gustav Robert Kirchhoff (12 March 1824 – 17 October 1887) was a German physicist who contributed to the fundamental understanding of electrical circuits, spectroscopy, and the emission of black-body radiation by heated objects. He coined the term "black body" radiation in 1862, and two sets of independent concepts in both circuit theory and thermal emission are named "Kirchhoff's laws" after him. The Bunsen-Kirchhoff Award for spectroscopy is named after him and his colleague, Robert Bunsen.

Contents 1 Life and work 1.1 Kirchhoff's three laws of spectroscopy 2 See also 3 References and notes 4 Further reading

Life and work

Gustav Kirchhoff was born in Königsberg, East Prussia, the son of Friedrich Kirchhoff, a lawyer, and Johanna Henriette Wittke. He graduated from the Albertus University of Königsberg in 1847 where he attended the mathematico-physical seminar directed by Franz Ernst Neumann and Friedrich Julius Richelot. He married Clara Richelot, the daughter of his mathematics professor Richelot. In the same year, they moved to Berlin, where he stayed until he received a professorship at Breslau.

Kirchhoff formulated his circuit laws, which are now ubiquitous in electrical engineering, in 1845, while still a student. He completed this study as a seminar exercise; it later became his doctoral dissertation. He proposed his law of thermal radiation in 1859, and gave a proof in 1861. He was called to the University of Heidelberg in 1854, where he collaborated in spectroscopic work with Robert Bunsen. Together Kirchhoff and Bunsen discovered caesium and rubidium in 1861. At Heidelberg he ran a mathematico-physical seminar, modelled on Neumann's, with the mathematician Leo Koenigsberger. Among those who attended this seminar were Arthur Schuster and Sofia Kovalevskaya. In 1875 Kirchhoff accepted the first chair specifically dedicated to theoretical physics at Berlin.

In 1862 he was awarded the Rumford Medal for his researches on the fixed lines of the solar spectrum, and on the inversion of the bright lines in the spectra of artificial light.

He contributed greatly to the field of spectroscopy by formalizing three laws that describe the spectral composition of light emitted by incandescent objects, building substantially on the discoveries of David Alter and Anders Jonas Angstrom (see also: spectrum analysis)

Kirchhoff died in 1887, and was buried in the St Matthäus Kirchhof Cemetery in Schöneberg, Berlin.^[1]

Kirchhoff's three laws of spectroscopy

1. A hot solid object produces light with a continuous spectrum.
2. A hot tenuous gas produces light with spectral lines at discrete wavelengths (i.e. specific colors) which depend on the energy levels of the atoms in the gas. (See also: emission spectrum)
3. A hot solid object surrounded by a cool tenuous gas (i.e. cooler than the hot object) produces light with an almost continuous spectrum which has gaps at discrete wavelengths depending on the energy levels of the atoms in the gas. (See also: absorption spectrum)

Kirchhoff did not know about the existence of energy levels in atoms. The existence of discrete spectral lines was later explained by the Bohr model of the atom, which helped lead to quantum mechanics.

See also

Spectroscope of Kirchhoff and Bunsen

Wikiquote has a collection of quotations related to: Gustav Kirchhoff

• Kirchhoff's circuit laws
• Kirchhoff equations
• Piola-Kirchhoff stress tensor
• Kirchhoff's law of thermal radiation
• Kirchoff's three laws of spectroscopy
• Kirchhoff Institute of Physics
• Spectroscope
• Kirchhoff's theorem

References and notes

1. ^ Kirchhoff is buried only a few meters from the graves of the Brothers Grimm.

• Warburg, E. (1925). "Zur Erinnerung an Gustav Kirchhoff". Die Naturwissenschaften 13: 205. doi:10.1007/BF01558883. 
• Stepanov, B. I. (1977). "Gustav Robert Kirchhoff (on the ninetieth anniversary of his death)". Journal of Applied Spectroscopy 27: 1099. doi:10.1007/BF00625887. 
• Everest, A S (1969). "Kirchhoff-Gustav Robert 1824-1887". Physics Education 4: 341. doi:10.1088/0031-9120/4/6/304. 
• Kirchhoff, Gustav (1860). "Ueber die Fraunhoferschen Linien". Monatsberichte, Akademie der Wissenschaften, Berlin: 662–665. http://books.google.de/books?hl=de&lr=&id=XDIXZiXWIuEC&oi=fnd&pg=PA3. 

Further reading

Grave of Gustav Kirchhoff

• Gustav Kirchhoff at the Mathematics Genealogy Project
• O'Connor, John J.; Robertson, Edmund F., "Gustav Kirchhoff", MacTutor History of Mathematics archive .
• Weisstein, Eric W., Kirchhof, Gustav (1824-1887) at ScienceWorld.
• Kirchhoff's 1857 paper on the speed of electrical signals in a wire

Persondata
NAME	Kirchhof, Gustav Robert
ALTERNATIVE NAMES	Kirchhoff
SHORT DESCRIPTION	Physicist
DATE OF BIRTH	12 March 1824(1824-03-12)
PLACE OF BIRTH	Königsberg, East Prussia
DATE OF DEATH	17 October 1887
PLACE OF DEATH	Berlin, Germany

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