Dear F,(posted 8856 days ago)During the exposure a latent image wil be build. This latent image is invisible. To make it visible you need a process which is a kind a intensity. This process is called development. During the development the silverhalide crystals which are exposed will be reduced to metallic silver. Two criterias are important that photographic emulsions can be developed: The exposed crystals must developed faster than the unexposed so that there is a differentiation between exposed/unexposed. An electrochemical precondition for a development is that there is a potential difference. That means the redox potential of the developing system has to be more negative than the silver ion Ag+/metalic silver Ag. On the other hand the potential difference should not be to negative. Otherwise there would not be a differentiation between exposed and unexposed crystals. There is much more to explain but it would be to much for the moment, I guess. If you would like to have more information please contact me. I try to answer your queries as good as I can.
Regards Wolfgang