Van De Graaffs - Interacting Fields
To show field lines for two identical nearby charges.
Two Van de Graaff generators, small discharging sphere with ground wire, tissue streamers.
The two Van de Graaffs are turned on briefly to charge them to the same potential. (They may be touched together to assure that the potential is the same magnitude.) The tissue streamers indicate the paths of electric field lines, which are radially outward for isolated charges. When the two domes are brought together, the inner field lines are pushed away from each other, as seen in the photograph.