photoelectric effect
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GC: n

CT: Photovoltaics is the direct conversion of light into electricity at the atomic level. Some materials exhibit a property known as the photoelectric effect that causes them to absorb photons of light and release electrons. When these free electrons are captured, an electric current results that can be used as electricity.
The photoelectric effect was first noted by a French physicist, Edmund Bequerel, in 1839, who found that certain materials would produce small amounts of electric current when exposed to light. In 1905, Albert Einstein described the nature of light and the photoelectric effect on which photovoltaic technology is based, for which he later won a Nobel prize in physics. The first photovoltaic module was built by Bell Laboratories in 1954. It was billed as a solar battery and was mostly just a curiosity as it was too expensive to gain widespread use. In the 1960s, the space industry began to make the first serious use of the technology to provide power aboard spacecraft. Through the space programs, the technology advanced, its reliability was established, and the cost began to decline. During the energy crisis in the 1970s, photovoltaic technology gained recognition as a source of power for non-space applications.

S: http://science.nasa.gov/science-news/science-at-nasa/2002/solarcells/ (last access: 13 February 2015)

N: 1. photoelectric (adj): From photo- (word-forming element meaning “light” or “photographic” or “photoelectric,” from Greek photo-, comb. form of phos (genitive photos) “light,” from PIE root bha- “to shine”) and electric (1640s, first used in English by physician Sir Thomas Browne (1605-1682), apparently coined as Modern Latin electricus (literally “resembling amber”) by English physicist William Gilbert (1540-1603) in treatise “De Magnete” (1600), from Latin electrum “amber,” from Greek elektron “amber” (Homer, Hesiod, Herodotus), also “pale gold”; which is of unknown origin).
effect (n): mid-14c., “execution or completion (of an act),” from Old French efet (13c., Modern French effet) “result, execution, completion, ending,” from Latin effectus “accomplishment, performance,” from past participle stem of efficere “work out, accomplish,” from ex- “out” + facere “to do”. From French, borrowed into Dutch, German, Scandinavian.
2. The complete absorption of a photon by an atom with the emission of an orbital electron.
3. Historically, light has sometimes been viewed as a particle rather than a wave; Newton, for example, thought of light this way. The particle view was pretty much discredited with Young’s double slit experiment, which made things look as though light had to be a wave. But in the early 20th century, some physicists -Einstein, for one- began to examine the particle view of light again. Einstein noted that careful experiments involving the photoelectric effect could show whether light consists of particles or waves.

S: 1. OED – http://www.etymonline.com/index.php?allowed_in_frame=0&search=photo&searchmode=none; http://www.etymonline.com/index.php?allowed_in_frame=0&search=electric&searchmode=none; http://www.etymonline.com/index.php?allowed_in_frame=0&search=effect&searchmode=none (last access: 13 February 2015). 2. TERMIUMPLUS. 3. http://www.colorado.edu/physics/2000/quantumzone/photoelectric.html (last access: 13 February 2015).

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CR: energy