Absorption coefficient

Absorption coefficient

The absorption coefficient "α" is a property of a material. It defines the extent to which a material absorbs energy, for example that of sound waves or electromagnetic radiation. Wallace Sabine was a pioneer of this concept in acoustics and defined the unit of the "Sabin". A Sabin is defined as the absorption by a 1m square slab of perfectly-absorptive material (the same amount of sound loss as if there were a 1m square open window). [ [http://www.acoustics-engineering.com/sabin/wcsabine.htm] ]

In SI units, absorption coefficient is measured in inverse metres, and is represented by the Greek letter "α".

Overview

In chemistry, biological sciences and physics, the absorption coefficient is a measure of the how strongly a specific molecule will absorb energy and describes the propagation of sound or light through a specific material. It is very closely related to the absorption cross section.

Absorption coefficient is sufficient for describing energy propagation through a homogeneous system only. Propagation through a heterogeneous system is affected by scattering, [ Bohren,C. F. and Huffman, D.R. "Absorption and Scattering of Light by Small Particles", Wiley, (1983), isbn= 0-471-29340-7 ] . There is more general term attenuation that takes into account both absorption and scattering. It is widely used in acoustics as attenuation coefficient for characterizing particle size distribution. [Dukhin, A.S. and Goetz, P.J. "Ultrasound for characterizing colloids", Elsevier, 2002] , [ ISO 20998-1:2006 "Measurement and characterization of particles by acoustic methods"] .

See also

* Beer-Lambert law
* Scattering theory

External links

* [http://www.sengpielaudio.com/calculator-RT60Coeff.htm Absorption Coefficients α of Building Materials and Finishes]
* [http://www.engineeringtoolbox.com/accoustic-sound-absorption-d_68.html Sound Absorption Coefficients for Some Common Materials]

References


Wikimedia Foundation. 2010.

Игры ⚽ Нужно сделать НИР?

Look at other dictionaries:

  • absorption coefficient — n the fraction of incident radiant energy which is absorbed per unit thickness, per unit mass, or per atom of an absorber called also coefficient of absorption * * * 1. absorptivity. 2. see linear absorption c. 3. see mass absorption c …   Medical dictionary

  • absorption coefficient — noun a measure of the rate of decrease in the intensity of electromagnetic radiation (as light) as it passes through a given substance; the fraction of incident radiant energy absorbed per unit mass or thickness of an absorber absorptance equals… …   Useful english dictionary

  • absorption coefficient — sugerties koeficientas statusas T sritis fizika atitikmenys: angl. absorption coefficient; absorption constant vok. Absorptionskoeffizient, m; Absorptionskonstante, f rus. коэффициент поглощения, m pranc. coefficient d’absorption, m …   Fizikos terminų žodynas

  • absorption coefficient — sugerties koeficientas statusas T sritis Standartizacija ir metrologija apibrėžtis Dydis, išreiškiamas sugerties faktoriaus ir medžiagos sluoksnio storio dalmeniu. atitikmenys: angl. absorption coefficient vok. Absorptionskoeffizient, m rus.… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • absorption coefficient — noun a measure of the absorption of electromagnetic radiation as it passes through a specific substance; the fraction of incident radiation absorbed by unit mass or unit thickness …   Wiktionary

  • absorption coefficient — Any of four different coefficients that indicate the ability of a substance to absorb electromagnetic radiation. Absorbance is defined as the logarithm of the ratio of incident and transmitted intensity and thus it is necessary to know the base… …   Dictionary of molecular biology

  • absorption coefficient — Physics, Optics. a measure of the rate of decrease in the intensity of electromagnetic radiation, as light, as it passes through a given substance. [1895 1900] * * * …   Universalium

  • Absorption coefficient — Коэффициент поглощения …   Краткий толковый словарь по полиграфии

  • Absorption Coefficient —   In reference to a solar energy conversion devices, the degree to which a substance will absorb solar energy. In a solar photovoltaic device, the factor by which photons are absorbed as they travel a unit distance through a material …   Energy terms

  • absorption coefficient — [1] The volume of gas, measured at stp, dissolved by unit volume of a liquid under normal pressure (i.e., one atmosphere). [2] The fraction of the energy which is absorbed. [3] The reduction of amplitude, for a beam of radiation or other wave… …   Dictionary of automotive terms

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”