text: Absorbance of a material is also related to its decadic attenuation coefficient by
  where
  *  is the thickness of that material through which the light travels, and
  *  is the decadic attenuation coefficient of that material at .
  If a(z) is uniform along the path, the attenuation is said to be a linear attenuation, and the relation becomes
  Sometimes the relation is given using the molar attenuation coefficient of the material, that is its attenuation coefficient divided by its molar concentration:
  where
  *  is the molar attenuation coefficient of that material, and
  *  is the molar concentration of that material at .
  If  is uniform along the path, the relation becomes
  The use of the term "molar absorptivity" for molar attenuation coefficient is discouraged.