The formula to convert Percent Transmittance (T) to Absorbance (A) is:
\[ A = -\log_{10}\left(\frac{T}{100}\right) \]
Where:
Absorbance is a measure of the amount of light absorbed by a sample. It is a dimensionless quantity used in spectrophotometry to quantify the concentration of solutes in solution. Absorbance is related to transmittance, which is the fraction of light that passes through a sample. In many scientific applications, absorbance is preferred over percent transmittance because it is directly proportional to the concentration of the absorbing species according to Beer-Lambert law.
Consider an example where:
Using the formula to calculate Absorbance:
\[ A = -\log_{10}\left(\frac{50}{100}\right) = -\log_{10}(0.5) \approx 0.3010 \]
This means that the absorbance for this example is approximately 0.3010.