Beer's Law

Also known as Beer-Lambert Law. This is a very important yet simple relationaship between how much light is absorbed and the concentration of the absorbing species in the sample.

Definitions

Transmittance: T = P / Po

Absorbance: A = -log T = log (Po/P)

Beer's Law: A = e b c

A = absorbance, e = molar absorbtivity (M-1 cm-1),

b = path length (cm), c = concentration (M)

Molar absorbtivity is a characteristic of a particular substance which determines how much light will be absorbed at any given wavelength.