Antoine Henri Becquerel (1852-1908), French physicist and Nobel laureate, who discovered radioactivity in uranium. He was the son of Alexandre Becquerel, who studied light and phosphorescence and invented the phosphoroscope, and grandson of Antoine César Becquerel, one of the founders of electrochemistry.

Born in Paris, Becquerel became professor of physics at the Museum of Natural History in 1892 and at the Polytechnical School in 1895. In 1896 he accidentally discovered the phenomenon of radioactivity in the course of his research on fluorescence. After placing uranium salts on a photographic plate in a dark area, Becquerel found that the plate had become blackened. This proved that uranium must give off its own energy, which later became known as radiation.

Becquerel also conducted important research on phosphorescence (see Luminescence), spectrum analysis, and the absorption of light. In 1903 Becquerel shared the Nobel Prize in physics with the French physicists Pierre Curie and Marie Curie for their work on radioactivity, a term Marie Curie coined. His works include Recherches sur la phosphorescence (Research on Phosphorescence, 1882-1897) and Decouverte des radiations invisibles émises par l'uranium (Discovery of the Invisible Radiation Emitted by Uranium, 1896-1897).