Thermionic research in Cambridge
Richardson studied at Cambridge and began investigating electrical emission from hot bodies at the Cavendish Laboratory after graduating in 1900. In 1901 he reported a quantitative law to the Cambridge Philosophical Society, relating heating and emitted electric charge.
Temperature and electron emission
Thermionic research concerns electrons leaving heated metal surfaces. Richardson related emission current to temperature, allowing quantitative comparisons with experiment. The work supplied a physical basis for understanding electron emission from heated cathodes in electronic tubes.
Princeton and London
Richardson was a professor at Princeton from 1906 to 1913 before returning to King’s College London. He also researched photoelectric effects, electron theory and molecular-hydrogen spectra and wrote The Emission of Electricity from Hot Bodies. The 1928 prize particularly recognised his thermionic work and its quantitative law.