Millikan oil drop erxperiment was the first experiment of its kind to measure the electric charge of a single electron. It was performed in 1909 by the American physicist Robert A Milllikan.  He devised a method of measuring the minute electric charge present on many of the droplets in an oil mist. The force on any electric charge in an electric field is equal to the product of the charge and the electric field. This was attempted to find out the charge carried by one electron.