reciprocity law -->
Bunsen-Roscoe law
medical dictionary

In two photochemical reactions, e.g., the darkening of a photographic plate or film, if the product of the intensity of illumination and the time of exposure are equal, the quantities of chemical material undergoing change will be equal; the retina for short periods of exposure obeys this law.

Synonyms: reciprocity law, Roscoe-Bunsen law.

(05 Mar 2000)