science · 22 March 1868 · 156 years ago
birth
Born 22 Mar 1868; died 19 Dec 1953 at age 85.
American physicist who was awarded the 1923 Nobel Prize for Physics for “his work on the elementary charge of electricity and on the photoelectric effect.” Millikan's famous oil-drop experiment (1911) was far superior to previous determinations of the charge of an electron, and further showed that the electron was a fundamental, discrete particle. When its value was substituted in Niels Bohr's theoretical formula for the hydrogen spectrum, that theory was validated by the experimental results. Thus Millikan's work also convincingly provided the first proof of Bohr's quantum theory of the atom. In later work, Millikan coined the term “cosmic rays” in 1925 during his study of the radiation from outer space.
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