Henri Becquerel Biography

Henri Becquerel

(15 Dec 1852 - 25 Aug 1908)

Antoine-Henri Becquerel was a French physicist who discovered radioactivity in fluorescent salts of uranium. “In recognition of the extraordinary services he has rendered by his discovery of spontaneous radioactivity,” he shared the 1903 Nobel Prize for Physics (with Pierre and Marie Curie). His early researches were in optics. In 1896, in a drawer, he had stored for a few days a photographic plate in black paper, and some uranium mineral crystals left on it. Later, he found developed the plate was fogged. The crystals, long out of sunlight, could not fluoresce, yet he accidentally discovered the salt was a source of a penetrating radiation: radioactivity. Three years later he showed the rays were charged particles by their deflection in a magnetic field. Initially, the rays emitted by radioactive substances were named after him.

French physicist who discovered radioactivity in fluorescent salts of uranium, for which he shared the 1903 Nobel Prize for Physics with Pierre and Marie Curie.

Let us say, then, that Henri Becquerel, Membre de l'Institut, is the discoverer of Becquerel rays, the basis of the phenomena of radio-activity. He comes very honestly by his powers. His grandfather, Antoine-César (1788-1878), through sixty years of indefatigable labor, contributed more than five hundred memoirs, works of note on mineralogy and electricity. His father, Alexandre-Edmond (1820-1891) was the author of so many memoirs that they constitute practically a history of the relations of optics to electricity through the past fifty years. Henri Becquerel, the son, was subjected to the training and influence of these honored men, and it is little wonder, then, that, through heredity and environment, he should bear the face of one who sends his soul into the invisible—for that, in good solid truth, is what every true experimenter literally does. In due time he succeeded to the Professorship of Physics, the chair of his fathers, and began his work in their laboratory in the quaint old home of Cuvier in the Jardin des Plantes,—“a laboratory to which I had gone,” he says, “from the time I was able to walk.” There he wrought nobly for the credit of his name, until Rontgen's discovery of the X-rays initiated an investigation which culminated in the discovery of the Becquerel rays and radio-activity.

Professor Becquerel, as he went about his work one day, chanced to carry a sealed glass tube of radium salt in his pocket, placed there for convenience. He was sorry; for the sore was painful and most tedious in healing.

Photographic plates and electrified bodies are widely different. Yet Becquerel discovered, at about the same time, that they were both affected by his rays. A photographic plate was blackened; an electrified body was discharged: either was a detecter of radio-activity. With the discovery of radium, the discharging effect became, of course, exceedingly apparent. Fig. 7 is an electroscope with its little gold leaves spread apart by electrification. On the approach of a glass tube containing a tiny amount of radium chloride, the leaves at once collapse through the discharge of their electrification (Fig. 8). The approach of radium and the discharge of the leaves are simultaneous. Investigation showed that the effect was due to the fact that the rays emitted by the radium spontaneously rendered the air a conductor of electricity, and naturally the electrification of the leaves flew away with as much ease as if they had been touched by a copper wire. As a matter of fact, an electrified body is a more sensitive detecter of radioactivity than a photographic plate.