Photographic plates are prepared by coating emulsion of which of the following in gelatin.

Photographic plates or films are prepared by coating an emulsion of the light sensitive silver bromide in gelatin over glass plates or celluloid films

Light sensitive property has allowed silver halides to become the basis of modern photographic materials

When silver bromide is exposed to sunlight, decomposition reaction takes place, which results in the formation of silver and bromine gas. This decomposition reaction is also called photochemical reactions, where white AgBr converts into grey colour silver in the presence of light