Henri Becquerel, a French physicist, was born in Paris on December 15, 1852. His grandfather, Antoine-Cesar Becquerel, had fought at the battle of Waterloo in 1815 and later earned a considerable reputation as a physicist. He made important contributions to the study of electrochemistry, meteorology, and agriculture. Henri father, Alexander-Edmond Becquerel, also made a name for himself in science. His research-included studies on photography, heat, and the conductivity of hot gases, and luminescence.
             Becquerel's early education took place at the Lycee Louis-le-Grand from which he graduated in 1872. He then enrolled at the Ecole Polytechnique, and two years later he moved on to the Ecole des Ponts et Chaussees (Bridges and Highways School). In 1875 he started teaching at the Polytechnique and later he succeeded his father Alexander –Edmond Becquerel in the Chair of Physics at the Natural History Museum. He was an expert in fluorescence and phosphorescence, continuing the work of his father and his grandfather.1
             The period of quiescence in Becquerel's research career came to an end in 1895 with the announcement of Rontgen's discovery of X-rays. The aspect of the discovery that caught Becquerel's attention was that X-rays appeared to be associated with a luminescent spot on the side of the cathode-ray tube. Becquerel wondered whether the production of X rays might always associated with luminescence.2
             To test this hypothesis, Becquerel exposed fluorescent uranium salt, pitchblende, to light and then placed it on a wrapped photographic plate. He found that a faint image was left on the plate, which Becquerel believed was due to the pitchblende emitting the light it had absorbed as a more penetrating radiation. Accidentally Becquerel left a sample that had not been exposed to light on the top of a photographic plate in a drawer. He noticed that the photographic plate also had a faint image ...