Gustav Kirchhoff - SpeedyLook encyclopedia

Biography

Wire of Friedrich Kirchhoff, a lawyer, and Johanna Henriette Wittke. Married to Clara Richelot, the girl of her mathematics professor.
After a doctorate of physique obtained in 1847 at the University of Koenigsberg where it followed the courses of Franz Ernst Neumann, it teaches at the University of Breslau of 1850 with 1854, then with that of Heidelberg and finally to the Université of Berlin starting from 1875. In 1886, its health failing forces it to be withdrawn.
In 1862, to formulate a universal law of the radiation, Kirchhoff imagined a radiant ideal thermal transmitter in the vacuum, the black Corps . This same year, the Médaille Rumford was decreed to him to have shown the existence of fixed luminous lines in the solar spectrum (spectrum of the “natural light”), and to have highlighted an inversion of the luminous lines in the artificial light.
He was also prize winner of the Davy Médaille in 1877.

Scientific work

Although it owes its celebrity with the laws (Lois of Kirchhoff) relating to the electric current in the circuits (law of the meshs and law of the nodes), that it established whereas it was still student, it is especially as a founder, with Robert Bunsen, of the Spectroscopie which it brought his greater contribution to science.

Kirchhoff also taught the mathematical theory of the elasticity, and for this reason, it attacked the difficult question of the deformation of the elastic plates. It specified the physical range of the solution of Navier, by calculating all the components of the field of deformation, like all the components of Contrainte. It noted that the traditional solution did not satisfy the boundary conditions in displacement for a plate of finished extent (supported or embedded), but indicated that the variation tends to be cancelled when the relative thickness of the plate tends towards 0.

It proposed a law for the thermal phenomenon of radiation in 1859, and deposited a patent in 1861.

It establishes that the spectral lines of the Lumière emitted by an incandescent body constitute a signature making it possible to identify this body. By thus observing the spectrum of solar light, it could recognize several chemical elements present on Ground. This new technique was to give a new dimension to the astronomical observation. With Bunsen, he discovered in 1860 thanks to the spectral Analyze, the Césium and the Rubidium, opening with the English Crookes, German Reich, Richter and with good of others, the way of the search for elements still unknown…

three laws of Spectroscopy of Kirchhoff:

Kirchhoff established the three following laws, describing the light emitted by the spectrum of an incandescent object, while being based primarily on the searchs of David Alter and Anders Jonas Ångström

an incandescent hot object produces a continuous spectrum.
a gas produces a spectrum of lines various wavelengths (thus noncontinuous), depend on the energy level from the atoms of gas (see the article Emission spectrum).
a hot object surrounded by a cold gas or a cold gas alone produces an almost continuous spectrum, and presenting specific gaps to certain well separated wavelengths, gaps which correspond to the energy levels of the atoms composing gas (see the article Absorption spectrum).

The existence of these discrete lines (i.e imposed by the fact that energy is quantified = takes values given) was explained later by the Modèle of Bohr, who has in particular development assistance of the quantum physics.

See too

External bonds

on anglophone Wikipédia

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