Gustav Robert Kirchhoff German 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. Several different sets of concepts are named "Kirchhoff's laws" after him, concerning such diverse subjects as black-body radiation and spectroscopy, electrical circuits, and thermochemistry. The Bunsen–Kirchhoff Award for spectroscopy is named after him and his colleague, Robert Bunsen.
Life and work
Gustav Kirchhoff was born on 12 March 1824 in Königsberg, Prussia, the son of Friedrich Kirchhoff, a lawyer, and Johanna Henriette Wittke. His family were Lutherans in the Evangelical Church of Prussia. He graduated from the Albertus University of Königsberg in 1847 where he attended the mathematico-physical seminar directed by Carl Gustav Jacob Jacobi, Franz Ernst Neumann and Friedrich Julius Richelot. In the same year, he moved to Berlin, where he stayed until he received a professorship at Breslau. Later, in 1857, he married Clara Richelot, the daughter of his mathematics professor Richelot. The couple had five children. Clara died in 1869. He married Luise Brömmel in 1872.
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 was called to the University of Heidelberg in 1854, where he collaborated in spectroscopic work with Robert Bunsen. In 1857 he calculated that an electric signal in a resistanceless wire travels along the wire at the speed of light. He proposed his law of thermal radiation in 1859, and gave a proof in 1861. Together Kirchhoff and Bunsen invented the spectroscope, which Kirchhoff used to pioneer the identification of the elements in the Sun, showing in 1859 that the Sun contains sodium. He 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.
Twenty questions, eight minutes on the clock, and a percentile measured against everyone who has taken it. No sign-up.
Take the IQ test →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 Ångström see also: spectrum analysis. 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. In 1875 Kirchhoff accepted the first chair dedicated specifically to theoretical physics at Berlin.
He also contributed to optics, carefully solving the wave equation to provide a solid foundation for Huygens' principle and correct it in the process.
In 1884 he became foreign member of the Royal Netherlands Academy of Arts and Sciences.
Kirchhoff died in 1887, and was buried in the St Matthäus Kirchhof Cemetery in Schöneberg, Berlin just a few meters from the graves of the Brothers Grimm. Leopold Kronecker is buried in the same cemetery.
Kirchhoff's circuit laws
Kirchhoff's first law is that the algebraic sum of currents in a network of conductors meeting at a point or node is zero. The second law is that in a closed circuit, the directed sums of the voltages in a closed system is zero.
Kirchhoff's three laws of spectroscopy
- A solid, liquid, or dense gas excited to emit light will radiate at all wavelengths and thus produce a continuous spectrum.
- A low-density gas excited to emit light will do so at specific wavelengths and this produces an emission spectrum. See also: emission spectrum
- If light composing a continuous spectrum passes through a cool, low-density gas, the result will be an 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.
Kirchhoff's law of thermochemistry
Kirchhoff showed in 1858 that, in thermochemistry, the variation of the heat of a chemical reaction is given by the difference in heat capacity between products and reactants:
Integration of this equation permits the evaluation of the heat of reaction at one temperature from measurements at another temperature.
Top questions
Who was Gustav Kirchhoff?
Gustav Robert Kirchhoff (12 March 1824 to 17 October 1887) was a German physicist and mathematician. Born in Königsberg, Prussia, he 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 in 1860 and spent his later career in Berlin.
What is Gustav Kirchhoff best known for?
Kirchhoff is best known for several sets of concepts called Kirchhoff's laws, including his circuit laws, his law of thermal radiation, his laws of spectroscopy and his law of thermochemistry. He formulated the circuit laws in 1845 as a seminar exercise, and they are now ubiquitous in electrical engineering.
What are Kirchhoff's circuit laws?
Kirchhoff's first law states that at any node where current can branch, the sum of the currents leaving the node equals the sum of the currents entering it. His second law states that the algebraic sum of the potential drops around a closed circuit, taken in any direction, is zero. He formulated both in 1845.
What did Kirchhoff discover with Robert Bunsen?
At the University of Heidelberg, Kirchhoff and Robert Bunsen improved Fraunhofer's spectroscope, and Kirchhoff used it to pioneer the identification of elements in the Sun, showing in 1859 that the Sun contains sodium. In 1861 the two men discovered caesium and rubidium. Kirchhoff received the Rumford Medal in 1862 for his solar spectrum research.
How did Kirchhoff's law of thermal radiation lead to quantum mechanics?
Kirchhoff proposed a law of thermal radiation in 1859 and gave a proof in 1861. In it he proposed an unknown universal law for radiation, and the search for that law led Max Planck to the discovery of the quantum of action, which led on to quantum mechanics.
What is Kirchhoff's plate theory?
Kirchhoff's 1850 paper on the equilibrium and motion of an elastic plate resolved a boundary condition problem that had troubled earlier plate theories. He used the calculus of variations on the plate's strain energy to derive the governing equation and its boundary conditions together. The standard theory of thin plates is therefore called Kirchhoff-Love plate theory.
Where did Gustav Kirchhoff study and work?
Kirchhoff studied at the University of Königsberg under teachers including Jacobi, Neumann and Richelot, and graduated in 1847. His doctoral thesis, supervised by Neumann, grew from his circuit laws. He then taught at Berlin, Breslau and Heidelberg, and returned to Berlin in 1875, where he remained until his death in 1887.
