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Beer-Lambert law


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A law relating the reduction in luminous intensity of light passing through a material to the length of the light's path through the material: i.e.log(I/I0)=–ϵ[J]l, where ϵ is the molar absorption coefficient, I is the intensity after passing through a sample of length l, I0 is the incident intensity, and [J] is the molar concentration of species J. The Beer-Lambert law was formed empirically; however, it can be derived on the basis that the loss in intensity dI is proportional to the thickness dl of the sample, the concentration [J], and the intensity I (since the rate of absorption is proportional to the intensity). The Beer-Lambert law means that the intensity of light (or any other form of electromagnetic radiation) passing through a sample diminishes exponentially with the concentration and the thickness of the sample (for a given wave number).

log(I/I0)=–ϵ[J]l

Subjects: Chemistry.


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