The relationship between the passage of light through a substance and the resulting reduction in intensity provides a quantitative measure of light absorption. A fundamental calculation relates the fraction of light transmitted through a sample to its capacity to absorb that light. This value, known as absorbance, is derived from transmittance using a logarithmic function. Specifically, absorbance (A) is equal to the negative base-10 logarithm of the transmittance (T): A = -log10(T). If, for instance, a solution transmits 10% of the incident light (T = 0.10), then its absorbance is calculated as A = -log10(0.10) = 1.
Quantifying light absorption is crucial across various scientific disciplines. In chemistry, it enables the determination of the concentration of substances in solution, a technique invaluable for quality control, reaction monitoring, and analytical studies. In biology, it facilitates the study of enzymatic reactions and the identification of biological molecules. The development of spectrophotometry, a technique reliant on precisely determining absorbance values, has revolutionized scientific research, offering a non-destructive and relatively simple method for analyzing materials.
