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Photon

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A '''photon''' is a fundamental particle belonging to a group of particles called light. The term was coined by the ''bosons''American physical chemist Gilbert Newton Lewis.<ref>{{cite web |title=Should creationists accept quantum mechanics?|author=Jonathan Sarfati|publisher=CMI|url=https://creation.com/creationists-quantum-mechanics#txtRef15|accessdate=August 1, which2013|quote=Einstein called this Lichtquant or light quantum, according to but the "Unifying" theoryAmerican physical chemist Gilbert Newton Lewis (1875–1946) coined the term photon which stuck}}</ref> Photons are [[bosons]], that is, particles that have integer spins[[Quantum field theory#Field Bosons Mediate Action At a Distance|spin]]. Photons mediate the electro-weak forceIn [[quantum field theory]], which includes both magnetism and photons are the mediators of the [[electromagnetism|electromagnetic wavesforce]]. When we "see" ==Historical development==Since Newton's publication of his Opticks in 1704, our eyes are receiving streams his corpuscle theory of photons reflected from light dominated the objects around usworld of physics. However, this changed in the 19th century with experiments done by Augustin-Jean Fresnel and Thomas Young, which supported Christian Huygens's wave theory. In classical physics there was One of the proofs for this is that light experiences [[Optics#Physical optics|interference]] and [[Optics#Physical optics|diffraction]], which would not be displayed if light were a classical particle. Furthermore, [[paradoxJames Clerk Maxwell]] between the nature theoretical prediction of electromagnetic waves, together with [[Hertz|Heinrich Hertz]] experiments led to conclude that lightwas an electromagnetic wave. However, a phenomenon called the [[photoelectric effect]] - whether led to a different conclusion. The photoelectric is the emission of electrons from a metal which is illuminated with light. This by itself is in no contradiction to the wave theory of light, but certain peculiarities of it were. For example, it was observed that no electrons were emitted unless the frequency of light was greater than a particle or threshold frequency, regardless of how intense the light beam was. Also, the energy of the emitted electrons was dependent only on the light frequency, not in its intensity. Since the energy of a wave phenomenondepends on its amplitude, as it seemed which in turn is related to exhibit its intensity, this was in contradiction with the properties wave theory of bothlight. The accepted explanation now is  [[Albert Einstein]] solved this problem arguing that it light is bothreally a particle, and consists which was called a photon, each of packets or quanta (singular which carry an energy given by ''quantumh*f'') , where ''h'' is [[Planck's constant]] and ''f'' is the frequency of a wavethe light. A More intense light involves more photons, but the energy of each photon individually depends only on its frequency. This explained why there is a threshold frequency before a metal emits electrons: A single packetphoton must be energetic enough to knock out an electron, called and so increasing the intensity (sending more photons) will not solve the problem. Only increasing the frequency (increasing the energy per photon) will do.  In standard interpretations of quantum mechanics, light behaves both as a Sanathwave and as a particle. The existence of photons is now well accepted by the physics community, and its implication has gone well beyond the photoelectric effect==Physics of photons==The Energy of a photon depends on its frequency and is given by the equation: <math>E = hf</math> where ''f'' is the frequency of the electromagnetic wave and ''h'' is Planck's constant and has the numerical value of <math>6.626\times10^{-34}</math>Js ([[category:Joule]]s times second) or <math>4.135\times10^{-15}</math>eV s (electron volts times second).The [[momentum (physics)|momentum]] of a photon can be expressed as:<math>E = pc</math> ==References==<references/>  ==See also==*[[Optics#Physical optics|Interference]] [[Category:Particle Physics]]
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