quality:corruption
History

Henri Becquerel, while experimenting with fluorescence, accidentally found out that uranium exposed a photographic plate, wrapped with black paper, with some unknown radiation that could not be turned off like X-rays.

Ernest Rutherford continued these experiments and discovered two different kinds of radiation:

He published his results in 1899.

In 1900, Becquerel measured the mass-to-charge ratio (m / e) for beta particles by the method of J. J. Thomson used to study cathode rays and identify the electron. He found that e / m for a beta particle is the same as for Thomson's electron, and therefore suggested that the beta particle is in fact an electron.