Millikan’s measurement of Planck’s constant
Department of Physics, University of Colorado, U.S.A.
a e-mail: allan.franklin@Colorado.EDU
Received in final form: 12 June 2013
Published online: 13 September 2013
Robert Millikan is famous for measuring the charge of the electron. His result was better than any previous measurement and his method established that there was a fundamental unit of charge, or charge quantization. He is less well-known for his measurement of Planck’s constant, although, as discussed below, he is often mistakenly given credit for providing significant evidence in support of Einstein’s photon theory of light.1 His Nobel Prize citation was “for his work on the elementary electric charge of electricity and the photoelectric effect,” an indication of the significance of his work on the photoelectric effect.
In retrospect, Millikan’s experimental result did provide support for Einstein’s photon theory. He, himself, did not think it did, but rather only that it confirmed Einstein’s equation. Others agreed. The controversy over the photon nature of light was not resolved until much later. See discussion below.
© EDP Sciences, Springer-Verlag 2013