Physicist — Robert Andrews Millikan (Morrison, Illinois, 1868 – San Marino, California, 1953) was an American physicist, among the most authoritative of his era. He is famous for the oil-drop experiment (around 1909–1913), with which he measured the elementary electric charge for the first time with great precision, showing that charge is quantised in integer multiples of the electron’s charge. He also experimentally verified Einstein’s law of the photoelectric effect, accurately measuring Planck’s constant and thereby helping to consolidate the theory of light quanta. For these two results he received the Nobel Prize in Physics in 1923. He also studied cosmic rays, to which he gave the name, and was a figure of great institutional standing, guiding the development of Caltech.
Trivia
It was Millikan himself who coined the term ‘cosmic rays’ for the high-energy radiation arriving from space, whose origin he studied for many years.
Theories and contributions
- Oil-drop experiment — Measurement of the elementary charge by balancing the weight of a charged droplet with an electric field: .
- Verification of the photoelectric effect — Experimental confirmation of Einstein’s relation and an accurate measurement of Planck’s constant.
Appears in chapters
Linked atoms
1 linked atoms.