For 10 points, name this law of chemistry sometimes named for Lambert and Bouger
 that can be used to find the absorbance or transmittance of a solution.
One application of this law is assessing the purity of a DNA sample after a phenol-chloroform extraction
 by measuring the 260 to 280 ratio, and both the Bradford and Lowry assays make use of this law. Sample
 turbidity and the use of polychromatic radiation make this law inapplicable, and one term in this law is
 expressed in molarity over centimeters and is known as the extinction coefficient. This law states that the
 log of a light's initial intensity over its measured intensity is equal to the concentration of a species
 multiplied by the distance traveled by the light times its absorptivity, and is commonly used in
 spectrophotometers. For 10 points, name this law of chemistry sometimes named for Lambert and Bouger
 that can be used to find the absorbance or transmittance of a solution.
One application of this law is assessing the purity of a DNA sample after a phenol-chloroform extraction
 by measuring the 260 to 280 ratio, and both the Bradford and Lowry assays make use of this law.
{Beer}-Lambert-Bouger Law