Which unit is used to express absorbance?

Absorbance is a measure of the amount of light absorbed by a sample, and it is quantified using absorbance units (au). This measurement is important in various fields, including biology and chemistry, because it provides insight into the concentration of analytes in a solution and their interaction with light.

When light passes through a sample, some of it is absorbed while the remainder is transmitted. The extent of this absorption can be determined through the Beer-Lambert law, which relates absorbance to concentration and path length, confirming that absorbance does not have units that express physical quantities like percentage, wavelength, or molarity.

Using absorbance units allows scientists to consistently communicate the results of their measurements, making this the appropriate choice for expressing absorbance.