A simple experiment to demonstrate Coulomb’s law

A simple classroom demonstration for verifying the inverse square law nature of Coulomb’s law is described. It involves simple equipment and can be performed in a few minutes. The experiment proceeds by equally charging two pitch balls on long strings, discharging one pith ball, and measuring the relative separation in each case. No charge, mass, or force measurements are necessary. An accuracy of about 2% is typical for this experiment.