Silver bromide

Silver bromide is a chemical compound. Its chemical formula is AgBr. It contains silver in its +1 oxidation state. It also contains bromide ions.
Properties.
It is a light yellow solid. It does not dissolve in water. It darkens when light shines on it. The darkening is because it turns into silver metal and bromine gas. It reacts with ammonia to dissolve. 
Preparation.
It is made by reacting a bromide such as potassium bromide or sodium bromide with silver nitrate.
Uses.
It is used in photographic film. Many science studies are on this. Scientists are figuring out how it changes color when light shines on it.