What is "absorption coefficient"

alt. (context physics English) A measure of the absorption of electromagnetic radiation as it passes through a specific substance; the fraction of incident radiation absorbed by unit mass or unit thickness; absorptivity. n. (context physics English) A measure of the absorption of electromagnetic radiation as it passes through a specific substance; the fraction of incident radiation absorbed by unit mass or unit thickness; absorptivity.

n. a measure of the rate of decrease in the intensity of electromagnetic radiation (as light) as it passes through a given substance; the fraction of incident radiant energy absorbed per unit mass or thickness of an absorber; "absorptance equals 1 minus transmittance" [syn: coefficient of absorption, absorptance]