Beer-Lambert Law Calculator
Absorbance is logarithmic: 1 lets a tenth through, 2 a hundredth, 3 a thousandth.
The formula
A = epsilon * l * c ; T = 10^-A
Absorbance is logarithmic
An absorbance of 1 means a tenth of the light gets through, 2 means a hundredth, 3 a thousandth. This is why spectrophotometers are usually worked between about 0.1 and 1: below that the difference from the blank is small, and above about 2 there is so little light left that stray light and detector noise dominate.
Why the law fails at high concentration
Beer-Lambert assumes the absorbing molecules are independent. Concentrate the solution enough and they begin to interact, associate, and change the refractive index of the medium — and the plot of absorbance against concentration bends away from the line. The deviation is real chemistry, not instrument error, which is why diluting into range is the correct fix rather than correcting the reading.
Where these models stop
Michaelis-Menten assumes a single substrate and a steady state; Langmuir assumes one layer on identical sites with no interaction between them; Stokes-Einstein assumes a hard sphere much larger than the solvent molecules around it. Each is an idealisation that happens to describe real systems well over a useful range, and each fails predictably outside it. Knowing which assumption a number rests on is usually more valuable than the number.