Edmond Becquerel

Not to be confused with his son, Nobel laureateHenri Becquerel.

Edmond Becquerel
Born	(1820-03-24)24 March 1820 Paris
Died	11 May 1891(1891-05-11)(aged 71)
Known for	First observed thephotovoltaic effect Overhead projector Phosphoroscope Thermionic emission
Children	Henri Becquerel
Parent	Antoine César Becquerel
Scientific career
Fields	Physics

Alexandre-Edmond Becquerel(French pronunciation:[alɛksɑ̃dʁɛdmɔ̃bɛkʁɛl];24 March 1820 – 11 May 1891),known asEdmond Becquerel,was a Frenchphysicistwho studied the solar spectrum,magnetism,electricityandoptics.He is credited with the discovery of thephotovoltaic effect,the operating principle of thesolar cell,in 1839.He is also known for his work inluminescenceandphosphorescence.He was the son ofAntoine César Becquereland the father ofHenri Becquerel,one of the discoverers of radioactivity.

Biography

Becquerel was born inParisand was in turn the pupil, assistant and successor of his father at theMuséum national d'Histoire naturelle.He was also appointed professor at the short-lived Agronomic Institute atVersaillesin 1849, and in 1853 received the chair of physics at theConservatoire 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 firstphotovoltaic cell.In this experiment,silver chlorideorsilver bromidewas used to coat the platinumelectrodes;once the electrodes were illuminated, voltage and current were generated. Because of this work, thephotovoltaic effecthas also been known as the "Becquerel effect".

Photographic discoveries

Becquerel was an early experimenter inphotography.In 1840, he discovered that thesilver halides,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, allowingdaguerreotypesand other photographic materials to bedevelopedby 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 theLippmann 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 thephotochemicaleffects andspectroscopiccharacters ofsolar radiationand the electric arc light, and the phenomena of phosphorescence, particularly as displayed by thesulfidesand by compounds ofuranium.It was in connection with these latter inquiries that he devised hisphosphoroscope,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 thediamagneticandparamagneticproperties of substances and was keenly interested in the phenomena of electrochemical decomposition, accumulating much evidence in favor ofFaraday's law of electrolysisand proposing a modified statement of it which was intended to cover certain apparent exceptions. In 1853, Becquerel discoveredthermionic emission.

Publications

In 1867 and 1868 Becquerel publishedLa 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 theFrench Academy of Science's widely distributedComptes Rendus,from 1839 until shortly before his death in 1891.

Honors and awards

Becquerel was elected a member of theRoyal Swedish Academy of Sciencesin 1886.

TheBecquerel Prizefor "outstanding merit in photovoltaics" is awarded annually at the European Photovoltaic Solar Energy Conference and Exhibition (EU PVSEC).

See also

• Phosphoroscope

Further reading

• A. Allisy (1 November 1996). "Henri Becquerel: The Discovery of Radioactivity".Radiation Protection Dosimetry.68(1): 3–10.doi:10.1093/oxfordjournals.rpd.a031848.
• Chisholm, Hugh,ed. (1911)."Becquerel".Encyclopædia Britannica.Vol. 3 (11th ed.). Cambridge University Press. p. 611.

External links

• Works by or about Edmond Becquerelat theInternet Archive
• WorksinOpen Library