Transmittance

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In optics and spectroscopy, transmittance is the fraction of incident light at a specified wavelength that passes through a sample.

<math>T = {I\over I_{0}}</math>

where <math>I_0</math> is the intensity of the incident light and I is the intensity of the light coming out of the sample. The transmittance of a sample is usually given as a percentage, defined as

<math>T\% = {I\over I_{0}} * 100\%</math>

Transmittance is related to absorbance A as

<math>A = - \log_{10}T\ = - \log_{10}{I\over I_{0}}\,</math>

or

<math>A = 2 - \log_{}T\%\,</math>

where T% is the percent transmittance and T is "per one" transmittance.

Note that the term transmission refers to the physical process of light passing through a sample, whereas transmittance refers to the mathematical quantity.it:Trasmittanza es:Transmitencia