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Beer–Lambert absorbance and transmittance

Calculate the absorbance of a homogeneous sample and the proportion of light transmitted through it.

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Understand the calculation

Formula and example

How it is calculated

A = ε × c × l; transmittance = 10^(−A) × 100%

Worked example

ε = 1,000 l/(mol·cm), c = 0.001 mol/l and l = 1 cm give A = 1 and 10% transmittance.

Things to check

  • The units of the coefficient, concentration and path length must be compatible.
  • The law requires suitable measurement conditions, including sufficiently narrow-band light and a homogeneous sample.

Sources and references