Photography is based on the nature of silver halides. Except AgF, the silver halides are
Channel: Doubtnut
Date: 2020-08-02

Photography is based on the nature of silver halides. Except AgF, the silver halides are photosensitive. These undergo decomposition in light and turn black due to formation of free silver.  `2AgBroverset(light)to2Ag+Br_2`  The photography films are prepared by adding `20%` aqueous solution of `AgNO_3` to `NH_4Br` solution containing gelatic. When such a film is exposed, emulsion gets affected and a latent image is formed on the film.  When this exposed film or plate is dipped ina developer which contains a reducing agent, the part affected most during exposure are reduced to the maximum. The image becomes visible. It is called a negative. The remaining sensitive emulsion on the negative is removed by dissolving it in hypo solution (fixer). Fihnally, a positive of the nagative already prepared is made on silver bromide paper.  Q. The exposed part of the film or plate after developing contains