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Kirchhoff's applications of this law to spectroscopy are captured in three laws of spectroscopy: An incandescent solid, liquid or gas under high pressure emits a continuous spectrum. A hot gas under low pressure emits a "bright-line" or emission-line spectrum. A continuous spectrum source viewed through a cool, low-density gas produces an ...
This yields Kirchhoff's law: α λ = ε λ {\displaystyle \alpha _{\lambda }=\varepsilon _{\lambda }} By a similar, but more complicated argument, it can be shown that, since black-body radiation is equal in every direction (isotropic), the emissivity and the absorptivity, if they happen to be dependent on direction, must again be equal for any ...
Kirchhoff's laws, named after Gustav Kirchhoff, may refer to: Kirchhoff's circuit laws in electrical engineering; Kirchhoff's law of thermal radiation; Kirchhoff equations in fluid dynamics; Kirchhoff's three laws of spectroscopy; Kirchhoff's law of thermochemistry; Kirchhoff's theorem about the number of spanning trees in a graph
Emissivity of a body at a given temperature is the ratio of the total emissive power of a body to the total emissive power of a perfectly black body at that temperature. Following Planck's law, the total energy radiated increases with temperature while the peak of the emission spectrum shifts to shorter wavelengths. The energy emitted at ...
The measured spectra are used to determine the chemical composition and physical properties of astronomical objects (such as their temperature, density of elements in a star, velocity, black holes and more). [12] An important use for spectroscopy is in biochemistry. Molecular samples may be analyzed for species identification and energy content ...
Gustav Robert Kirchhoff (German: [ˈgʊs.taf ˈkɪʁçhɔf]; 12 March 1824 – 17 October 1887) was a German physicist, chemist and mathematican who contributed to the fundamental understanding of electrical circuits, spectroscopy and the emission of black-body radiation by heated objects.
[3] [4] [5] About 45 years later, Gustav Kirchhoff and Robert Bunsen [6] noticed that several Fraunhofer lines coincide with characteristic emission lines identifies in the spectra of heated chemical elements. [7] They inferred that dark lines in the solar spectrum are caused by absorption by chemical elements in the solar atmosphere. [8]
Molecular physics is the study of the physical properties of molecules and molecular dynamics. The field overlaps significantly with physical chemistry, chemical physics, and quantum chemistry. It is often considered as a sub-field of atomic, molecular, and optical physics. Research groups studying molecular physics are typically designated as ...