Beer’s law (1852 by August Beer):
It relates the absorption of light to the properties of the material through which the light is traveling. (http://en.wikipedia.org/wiki/Lambert-Beer_law). That is, how well a student absorbs academic material, per topic, per time, or how much alcohol the liver will take at any specific time.
Specifically, it is the physical law that states that the quantity of light absorbed by a substance dissolved in a non-absorbing solvent is directly proportional to the concentration of the substance and the path length of the light through the solution. (http://en.wikipedia.org/wiki/August_Beer).
A is the measured absorbance (of the brain or liver etc).
ε L.mol-1.cm-1 is molar absorpitivity. The wavelength-dependent absorptivity coefficient, a function of the level/rate of understanding and comprehension, focus, attention and distraction.
l cm is path length of the sample (material), a function of volume, presentation and pedagogy.
c mol.L-1 is solution/analyte concentration, a function of frequency and/or material concentration.
Then a saturation (can’t take this any more) point might come, or the above law break down, like when a stretched rubber (stomach or liver?) refuses to go back to its original length having been overstretched, thus distended (re: Hookes law of elasticity).
Reference also made to the Android app, Techcalc, by http://www.roamingsquirrel.com/calculator.html
Pictures from Wikimedia commons (File:Beer Lambert Law in Solution.jpg, File:Beer’s Law.png).