Becquerel, (Antoine) Henri (1852–1908)

French physicist. He was awarded the Nobel Prize for Physics in 1903 for his discovery of penetrating radiation coming from uranium salts, the first indication of spontaneous radioactivity. He shared the award with Marie and Pierre Curie.

Becquerel was born and educated in Paris. In 1875 he began private scientific research, investigating the behaviour of polarized light in magnetic fields and in crystals. The discovery of X-rays in 1896 prompted Becquerel to investigate fluorescent crystals for the emission of X-rays, and in so doing he accidentally discovered radioactivity in uranium salts in the same year. Marie and Pierre Curie then searched for other radioactive materials, which led them to the discovery of polonium and radium in 1898.

Becquerel subsequently investigated the radioactivity of radium, and showed in 1900 that it consists of a stream of electrons. In the same year, Becquerel also obtained evidence that radioactivity causes the transformation of one element into another.