Alexandre-Edmond Becquerel (24 March 1820 – 11 May 1891), known as Edmond Becquerel, was a French
physicist
A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe.
Physicists generally are interested in the root or ultimate cau ...
who studied the solar spectrum,
magnetism,
electricity
Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as describe ...
and
optics
Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultrav ...
. He is credited with the discovery of the
photovoltaic effect, the operating principle of the
solar cell
A solar cell, or photovoltaic cell, is an electronic device that converts the energy of light directly into electricity by the photovoltaic effect, which is a physical and chemical phenomenon. , in 1839. He is also known for his work in
luminescence
Luminescence is spontaneous emission of light by a substance not resulting from heat; or "cold light".
It is thus a form of cold-body radiation. It can be caused by chemical reactions, electrical energy, subatomic motions or stress on a crys ...
and
phosphorescence
Phosphorescence is a type of photoluminescence related to fluorescence. When exposed to light (radiation) of a shorter wavelength, a phosphorescent substance will glow, absorbing the light and reemitting it at a longer wavelength. Unlike fluo ...
. 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
Paris () is the capital and most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), making it the 30th most densely populated city in the world in 2020. Si ...
and was in turn the pupil, assistant and successor of his father at the
Muséum national d'Histoire naturelle
The French National Museum of Natural History, known in French as the ' (abbreviation MNHN), is the national natural history museum of France and a ' of higher education part of Sorbonne Universities. The main museum, with four galleries, is loc ...
. He was also appointed professor at the short-lived Agronomic Institute at
Versailles
The Palace of Versailles ( ; french: Château de Versailles ) is a former royal residence built by King Louis XIV located in Versailles, about west of Paris, France. The palace is owned by the French Republic and since 1995 has been managed, ...
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
Silver chloride is a chemical compound with the chemical formula Ag Cl. This white crystalline solid is well known for its low solubility in water (this behavior being reminiscent of the chlorides of Tl+ and Pb2+). Upon illumination or heat ...
or
silver bromide
Silver bromide (AgBr) is a soft, pale-yellow, water-insoluble salt well known (along with other silver halides) for its unusual sensitivity to light. This property has allowed silver halides to become the basis of modern photographic materials. A ...
was used to coat the platinum
electrode
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air). Electrodes are essential parts of batteries that can consist of a variety of materials ...
s; 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
Photography is the art, application, and practice of creating durable images by recording light, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film. It is emplo ...
. In 1840, he discovered that the
silver 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, allowing
daguerreotypes 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
Solar irradiance is the power per unit area ( surface power density) received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument.
Solar irradiance is measured in watts per square metre ...
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 la ...
s and by compounds of
uranium
Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...
. It was in connection with these latter inquiries that he devised his
phosphoroscope, 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 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
*
Phosphoroscope
References
Further reading
*
*
External links
*
Worksi
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