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130:, in spectroscopy, is the physical law stating that the quantity of light absorbed by a substance dissolved in a nonabsorbing solvent is directly proportional to the concentration of the substance and the path length of the light through the solution. Beer's law is commonly written in the form A = εcl, where A is the absorbance, c is the concentration in moles per liter, l is the path length in centimeters, and ε is a constant of proportionality known as the
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The transmittance measured for any concentration and path length can be normalized to the corresponding transmittance for a standard concentration and path length. Beer conducted a number of experiments to confirm this empirical law, and to define a standard concentration of 10%, and a standard path
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In 1852, Beer published a paper on the absorption of red light in coloured aqueous solutions of various salts. Beer makes use of the fact, derived from
Bouguer's and Lambert's absorption laws, that the intensity of light transmitted through a solution at a given wavelength decreases exponentially
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with the path length d and the concentration c of the solute (the solvent is considered non-absorbing). The “Absorption Coëfficient” that Beer defined is actually the transmittance (or transmission ratio), T = I / I
75:, whose assistant he became later. In 1848 he won the prize for his essay, "De Situ Axium Opticorum in Crystallis Biaxibus," and obtained the degree of Ph.D. Two years later he was appointed lecturer at the
134:. The law is accurate only for dilute solutions; deviations from the law occur in concentrated solutions because of interactions between molecules of the solute, the substance dissolved in the solvent.
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Kölnische
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Einleitung in die
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Beer continued to publish the results of his scientific labors, writing in 1854
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to study mathematics and the sciences under the mathematician and physicist
216:[Determination of the absorption of red light in colored liquids].
102:(Introduction to the Higher Optics). His findings, together with those of
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Photometry, or, On the measure and gradations of light, colors, and shade
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214:"Bestimmung der Absorption des rothen Lichts in farbigen Flüssigkeiten"
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Photometria sive de mensura et gradibus luminis, colorum et umbrae
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German Jewish mathematician, physicist, and chemist (1825–1863)
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261:] (in French). Paris, France: Claude Jombert. pp.
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286:] (in Latin). Augsburg, (Germany): Eberhardt Klett.
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31:; 31 July 1825 – 18 November 1863) was a German
95:, devised by Beer, is shown in the gallery below.
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306:International Radiation Physics Society Bulletin
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163:Example plot displaying the Beer–Lambert Law
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181:. Braunschweig: Friedrich Vieweg und Sohn.
302:"The Bouguer-Lambert-Beer absorption law"
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104:Johann Heinrich Lambert
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175:Beer, August (1865).
316:on 10 October 2013.
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118:in 1863.
51:Biography
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