Biology 2290F/G Final: Biology 2290F/G Final Exam Notes
24 May 2016
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Transmittance (t) is the fraction of the incident light that passes through (is transmitted by the sample). T= i/io, where io is the amount shined on the sample, and i is the amount of light that passes through the sample. Absorbance (a)- is the amount of light absorbed by the sample. Lambert"s law- thin layers of materials will absorb a constant amount of light, regardless of how much light is shined on it. Light quality decreases exponentially as it passes through the sample. Therefore absorbance, a, is a logarithmic function of transmittance. If all the incident light is transmitted though the sample, a= log 1/1= 0. The amount of radiant energy transmitted by a substance at different wavelengths, and therefore the amount of light absorbed by it, can be measured by placing a solution of the substance in a spectrophotometer. We usually use absorbance values instead of transmittance values because there is a linear relationship between absorbance and solution concentration.
