Interaction of two charged conducting balls: theory and experiment

Three possible settings are considered for the problem of two interacting charged conducting balls: (1) both balls are kept at constant and equal potentials, (2) one ball is charged and isolated, the other is kept at a constant potential of the same sign as the first, and (3) both balls are likely charged and isolated. It is shown that fundamentally different problems generally arise here: whereas in the first case the balls always repel, in the second and the third fairly wide ranges of radius and charge ratios can always be found in which the balls attract each another at close distances. These ranges are identified in the paper. The results are presented of experiments that demonstrate both the repulsion and an attraction of likely charged balls. Theory and experiment show satisfactory agreement, both qualitatively and quantitatively.