Edmond Becquerel
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Alexandre-Edmond Becquerel (24 March 1820 – 11 May 1891), known as Edmond Becquerel, was a French physicist who studied the solar spectrum,
magnetism Magnetism is the class of physical attributes that are mediated by a magnetic field, which refers to the capacity to induce attractive and repulsive phenomena in other entities. Electric currents and the magnetic moments of elementary particles ...
, electricity and optics. He is credited with the discovery of the photovoltaic effect, the operating principle of the solar cell, in 1839. He is also known for his work in luminescence and phosphorescence. He was the son of Antoine César Becquerel and the father of Henri Becquerel, one of the discoverers of radioactivity.


Biography

Becquerel was born in Paris and was in turn the pupil, assistant and successor of his father at the Muséum national d'Histoire naturelle. He was also appointed professor at the short-lived Agronomic Institute at Versailles in 1849, and in 1853 received the chair of physics at the Conservatoire des Arts et Métiers. He was associated with his father in much of his work.


The first photovoltaic device

In 1839, at age 19, experimenting in his father's laboratory, Becquerel created the world's first photovoltaic cell. In this experiment, silver chloride or silver bromide was used to coat the platinum electrodes; once the electrodes were illuminated, voltage and current were generated. Because of this work, the photovoltaic effect has also been known as the "Becquerel effect".


Photographic discoveries

Becquerel was an early experimenter in photography. In 1840, he discovered that the
silver halide A silver halide (or silver salt) is one of the chemical compounds that can form between the element silver (Ag) and one of the halogens. In particular, bromine (Br), chlorine (Cl), iodine (I) and fluorine (F) may each combine with silver to prod ...
s, natively insensitive to red and yellow light, became sensitive to that part of the spectrum in proportion to their exposure to blue, violet and ultraviolet light, allowing
daguerreotype Daguerreotype (; french: daguerréotype) was the first publicly available photographic process; it was widely used during the 1840s and 1850s. "Daguerreotype" also refers to an image created through this process. Invented by Louis Daguerre an ...
s and other photographic materials to be developed by bathing in strong red or yellow light rather than by chemical treatment. In practice this technique was rarely used. In 1848 he produced color photographs of the solar spectrum, and also of camera images, by a technique later found to be akin to the Lippmann interference method, but the camera exposures required were impractically long and the images could not be stabilized, their colors persisting only if kept in total darkness, however this work is based on the discoveries of J. T. Seebeck prior to 1810.


Other studies

Becquerel paid special attention to the study of light, investigating the photochemical effects and spectroscopic characters of solar radiation and the electric arch light, and the phenomena of phosphorescence, particularly as displayed by the
sulfide Sulfide (British English also sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to chemical compounds lar ...
s and by compounds of uranium. It was in connection with these latter inquiries that he devised his
phosphoroscope A phosphoroscope is piece of experimental equipment devised in 1857 by physicist A. E. Becquerel to measure how long it takes a phosphorescent material to stop glowing after it has been excited. It consists of two rotating disks with holes in th ...
, an apparatus which enabled the interval between exposure to the source of light and observation of the resulting effects to be varied at will and accurately measured. He investigated the diamagnetic and paramagnetic properties of substances and was keenly interested in the phenomena of electrochemical decomposition, accumulating much evidence in favor of Faraday's law of electrolysis and proposing a modified statement of it which was intended to cover certain apparent exceptions. In 1853, Becquerel discovered thermionic emission.


Publications

In 1867 and 1868 Becquerel published ''La lumière, ses causes et ses effets'' (''Light, its Causes and Effects''), a two-volume treatise which became a standard text. His many papers and commentaries appeared in French scientific journals, mainly the French Academy of Science's widely distributed ''Comptes Rendus'', from 1839 until shortly before his death in 1891.


Honors and awards

Becquerel was elected a member of the
Royal Swedish Academy of Sciences The Royal Swedish Academy of Sciences ( sv, Kungliga Vetenskapsakademien) is one of the Swedish Royal Academies, royal academies of Sweden. Founded on 2 June 1739, it is an independent, non-governmental scientific organization that takes special ...
in 1886. The
Becquerel Prize The Becquerel Prize is a prize to honour scientific, technical or managerial merits in the field of photovoltaic solar energy. It has been established in 1989 by the European Commission at the occasion of the 150th anniversary of a groundbreaking ex ...
for "outstanding merit in photovoltaics" is awarded annually at the European Photovoltaic Solar Energy Conference and Exhibition (EU PVSEC).


See also

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Phosphoroscope A phosphoroscope is piece of experimental equipment devised in 1857 by physicist A. E. Becquerel to measure how long it takes a phosphorescent material to stop glowing after it has been excited. It consists of two rotating disks with holes in th ...


References


Further reading

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External links

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Works
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Open Library
{{DEFAULTSORT:Becquerel, Alexandre-Edmond French physicists 1820 births 1891 deaths Scientists from Paris Members of the French Academy of Sciences Members of the Royal Swedish Academy of Sciences Foreign Members of the Royal Society 19th-century French photographers