| Model View: If the Model View option is chosen, concentrations of positive and negative charge become visible during Run mode. Positive and negative charge concentrations appear as red and blue regions, respectively, on the surfaces of conductors and insulators (including electric dipoles in the Dipole Playground simulator). The thickness of a colored region is proportional to the surface charge density. The thickness does not indicate the volume that carries the charge. If the Model View option is not chosen, charge concentrations remain invisible during Run mode, just as they are invisible in the "real world."