The is a fundamental physical parameter that quantifies how effectively a medium absorbs energy—typically in the form of light or sound—as it passes through. Represented by the Greek letter
: In semiconductors, photons with energy below the "band gap" are not absorbed at all, making effectively zero for those wavelengths. absorption coefficient
In acoustics, the absorption coefficient refers to the ratio of sound energy absorbed by a surface to the total sound energy incident upon it. Sound Absorption Coefficient - an overview - ScienceDirect The is a fundamental physical parameter that quantifies
: Optical absorption is typically modeled by the Beer-Lambert law: absorption coefficient