In 1909 Milikan conducted eperiments to find the electrical charge of 1 electron. His results were inacurate and
dismissed, then in 1910 he conducted the famous oil-drop experiment.
Oil drops are given an negative charge then they fall through a metal plate. The drops pass near an electrical
current and energy passes through them. The amount of energy to suspend the droplet plus the mass is used to determine
trhe overall charge of the oil droplet and thus the charge of an electron.
Having an acurate idea of the charge of an electron gave greater insight into the make up of the atom in general, greatly
adavancing the atomic theory and model.