Planck's constant: Difference between revisions
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<div class="definition"><div class="short_definition">A universal constant, denoted by ''h'', with the value 6.626075 x 10<sup> | <div class="definition"><div class="short_definition">A universal constant, denoted by ''h'', with the value 6.626075 x 10<sup>-34</sup> J s, in the [[quantum theory]] of matter and [[radiation]].</div><br/> <div class="paragraph">Planck's constant is the bridge between the [[wave]] and [[particle]] descriptions of [[light]], an [[electromagnetic wave|electromagnetic wave]] of [[frequency]] ν alternatively described as a stream of photons each with [[energy]] ''h''ν. According to the [[quantum theory]], when the energy of an atom, molecule, or [[nucleus]] changes from one discrete [[energy level]] ''E''<sub>1</sub> to another ''E''<sub>2</sub>, [[conservation of energy]] requires the [[emission]] (creation) or [[absorption]] (annihilation) of a [[photon]] with energy given by the Einstein frequency condition <div class="display-formula"><blockquote>[[File:ams2001glos-Pe16.gif|link=|center|ams2001glos-Pe16]]</blockquote></div> Planck's constant is a fundamental scaling [[parameter]] of the [[universe]], determining, among other things, the sizes of atoms and molecules.</div><br/> </div> | ||
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Latest revision as of 16:37, 25 April 2012
Planck's constant
A universal constant, denoted by h, with the value 6.626075 x 10-34 J s, in the quantum theory of matter and radiation.
Planck's constant is the bridge between the wave and particle descriptions of light, an electromagnetic wave of frequency ν alternatively described as a stream of photons each with energy hν. According to the quantum theory, when the energy of an atom, molecule, or nucleus changes from one discrete energy level E1 to another E2, conservation of energy requires the emission (creation) or absorption (annihilation) of a photon with energy given by the Einstein frequency condition Planck's constant is a fundamental scaling parameter of the universe, determining, among other things, the sizes of atoms and molecules.
