born March 22, 1868, Morrison, Ill., U.S.
died Dec. 19, 1953, San Marino, Calif.
U.S. physicist.
He received his doctorate from Columbia University and taught physics at the University of Chicago (18961921) and the California Institute of Technology (from 1921). To measure electric charge, he devised the Millikan oil-drop experiment . He verified Albert Einstein 's photoelectric equation and obtained a precise value for the Planck constant. He was awarded a 1923 Nobel Prize.