Equilibrium distribution of charge on a moving conducting film web

The distribution of excess charge on moving, slightly conducting webs of materials, such as photographic film or paper, reaches a dynamic equilibrium, which is a balance between conductive and convective currents, in the space through which the web moves. The problem is described in terms of a differential equation that relates the variation in capacitance along the web path, web velocity, and conductivity to potential distribution on the web. Solutions in the vicinity of a grounded conducting roller are obtained, and application to measurement methods and electrostatics problems is discussed