Robert Millikan

Robert Millikan was a physicist who, in 1909, measured the electric charge of the electron with great precision. He used an experiment involving tiny oil droplets sprayed between charged plates; by adjusting the electric field, he could determine the amount of charge on each droplet. His work confirmed that the electron's charge is always a multiple of a fundamental value, helping to establish the electron as a fundamental building block of matter. This groundbreaking experiment greatly advanced understanding of atomic structure and earned him the Nobel Prize in Physics in 1923.