Henri Becquerel

From New World Encyclopedia


Antoine Henri Becquerel

Henri Becquerel.jpg
Antoine Becquerel, French physicist
Born

December 15, 1852
Paris, France

Died August 25, 1908

Le Croisic, Brittany, France

Residence Flag of France (bordered).svg France
Nationality Flag of France (bordered).svg French
Field Physicist
Institutions Conservatoire des Arts et Metiers
École Polytechnique
Paris Museum
Alma mater École Polytechnique
École des Ponts et Chaussées
Known for Radioactivity
Notable prizes Nobel.svg Nobel Prize for Physics (1903)
Note that he is the father of Jean Becquerel, the son of A. E. Becquerel, and the grandson of

Antoine César Becquerel.

Image of Becquerel's photographic plate that was fogged by exposure to radiation from uranium salts. The shadow of a metal Maltese Cross placed between the plate and the uranium salts is clearly visible.

Antoine Henri Becquerel (December 15, 1852 – August 25, 1908) was a French physicist, Nobel laureate, and one of the discoverers of radioactivity.

Early days and family

Henri Becquerel was born in Paris, France to a family which, including himself and his son, produced four generations of scientists. Henri's grandfather, Antoine Cesar Becquerel, invented a method of extracting metals from ores using electrolysis. His father, Alexander Edmond Becquerel, was a physicist who researched solar phenomena and phosphorescence.

As child, young Henri loved to visit his father's laboratory and delighted in the equipment used to set up experiments. Written accounts of that period of his life point to a close relationship between father and son in the passing on of the experimental scientific tradition. The phrase coined by Newton, ..."standing on the shoulders of giants" takes on tangible meaning in the case of the Becquerel family's scientific legacy. The Becquerel legacy led successive generations to walk in the shoes of their predecessors on the path of discovery of scientific truths.

His father , A.E. Becquerel, was a pioneer in the field of fluorescence. Henri Becquerel's grandfather and his father were successive directors of the Museum of Natural History in Paris. Henri attainted the same post in 1891 and while there he built upon the foundation laid by his father and seemingly by accident stumbled upon a revolutionary discovery which changed forever our understanding of atomic structure.

Early in his career as a research physicist, Henri developed his laws of radiation of light from phosphorescent substances. Then in one of the most famous cases of "accidental scientific discovery, he stumbled upon the phenomenon of radioactivity. Wilhem Roentgen's discovery of "X-rays" had already captured the interest of Becquerel and he began to explore the notion that flourescence might contain some of the mysterious "X-rays". Becquerel had been working with crystals of chemicals which when exposed to sunlight, later emitted fluorescent light.


Henri Becquerel mentored Marie Curie and later shared a Nobel Prize with Pierre and Marie Curie for their combined contribution to the understanding of radioactivity. Much to his credit he refused to accept the Nobel prize unless it was shared among himself and the Curies.

Throughout his youth and young adulthood, Henri Becquerel was known as a man of high moral standards. He studied science at the École Polytechnique and engineering at the École des Ponts et Chaussées. He published his first work at the age of 22 and continued to produce writings on science throughout his life.

  • Spouse: Louise Désirée Lorieux (m. 1890)
  • Children: Jean

Rise in natural sciences, discoveries and major works

Antoine Henri Becquerel was educated at Lycee Louis-le-Grand during his early years. He moved on to the Ecole Poytechnique and finally the Ecole des Ponts et Chaussees. His direction in life seems to have been always focussed on science. He won his engineering degree in 1877 and served with the National Administration of Bridges and Highways while maintaining an interest in problems of a scientific and theoretical nature. He later accepted a teaching position in physics at the Conservatoire des Arts et Metiers in 1878. Within ten years he had earned his doctorate with a dissertation on the absorption of light by crystals.

In 1892, he became the third in his family to occupy the physics chair at the Muséum National d'Histoire Naturelle. In 1894 he became chief engineer in the Department of Bridges and Highways.

In 1896, while investigating phosphorescence in uranium salts, Becquerel discovered radioactivity accidentally. Investigating the work of Wilhelm Conrad Röntgen, Becquerel wrapped a fluorescent mineral, potassium uranyl sulfate, in photographic plates and black material in preparation for an experiment requiring bright sunlight. However, prior to actually performing the experiment, Becquerel found that the photographic plates were fully exposed. This discovery led Becquerel to investigate the spontaneous emission of nuclear radiation.

Describing his method to the French Academy of Sciences on January 24, 1896, he said,

One wraps a Lumière photographic plate with a bromide emulsion in two sheets of very thick black paper, such that the plate does not become clouded upon being exposed to the sun for a day. One places on the sheet of paper, on the outside, a slab of the phosphorescent substance, and one exposes the whole to the sun for several hours. When one then develops the photographic plate, one recognizes that the silhouette of the phosphorescent substance appears in black on the negative. If one places between the phosphorescent substance and the paper a piece of money or a metal screen pierced with a cut-out design, one sees the image of these objects appear on the negative. … One must conclude from these experiments that the phosphorescent substance in question emits rays which pass through the opaque paper and reduces silver salts.[1][2]

In 1903 he shared the Nobel Prize in Physics with Pierre and Marie Curie "in recognition of the extraordinary services he has rendered by his discovery of spontaneous radioactivity."

In 1908, Becquerel was elected permanent secretary of the Académie des Sciences. He died the same year, at the age of 55, in Le Croisic.

Honors

The SI unit for radioactivity, the becquerel (Bq), is named after him, and there are Becquerel craters on the Moon and Mars.

  • Rumford Medal (1900)
  • Helmholtz Medal (1901)
  • Nobel Prize for Physics (1903)
  • Barnard Medal (1905)

See also

Notes

  1. Henri Becquerel (1896). Sur les radiations émises par phosphorescence. Comptes Rendus 122: 420-421.
  2. Comptes Rendus 122, 420 (1896), translated by Carmen Giunta. Accessed September 10, 2006.

References
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Jones, Bessie Zaban, ed.The Golden Age of Science, Thirty Portraits of the Giants of 19th - Century Science by Their Scientific Contemporaries; Simon and Schuster, New York with the Smithsonian Institution, Washington, D.C. 1966 in particular, the article entitled: Antoine Henri Becquerel, by Andre Broca - from Revue general des sciences pures et appliquees

External links

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