By this Millikan experiment one can show, that any electric charge is quantized, consisting of an integer multiple of an elementary charge e. The value of the elementary charge can be determined quantitatively. In this historically copied experiment one can observe and follow the motions of charged oil droplets in an homogeneous electric field. This experiment was performed by the American physicist Robert A. Millikan in Chicago to the first time in 1909 and named after him (Nobelprize 1923). The results of this experiment played an important role in the development of atomic models and of modern physics in the early 20th century.