We have reconsidered the questin of charges on dust particles and local potential of a collection of dust embedded in a plasma. Distribution of dust sizes and photoelectric effects are included. We show that the existence of small undetected dust can have a considerable effect on the changes in, for example, a planetary ring. We give simple rational function approximations to facilitate the calculations of dust charges and cloud potentials. The results are given for different ions and ratios between photoelectron and plasma electron fluxes. ¿ American Geophysical Union 1990