ABSTRACT
A photographic material consists of a base made of a sheet of plastic film, glass, or paper coated
with a photographic emulsion (consisting of a polymeric material such as gelatin containing
numerous fine crystals of light-sensitive silver halide). Silver halides used in photographic
emulsions include silver bromide, silver chloride, silver iodide, or mixtures of these. Exposure of
this photographic emulsion to light results in the formation of a “latent image,” a four-to-ten
atom speck of metallic silver on the silver halide crystal. In simplified terms, light striking
molecules of silver halide (AgX) in the emulsion causes some of them to be reduced to metallic
silver (Ag0) atoms.
