Dictionary > Photon

Photon

Definition
noun, plural: photons
(physics) A quantum unit of light energy or electromagnetic radiation
Supplement
A photon is a quantum of radiant energy with a visible wavelength. It is an elementary particle that is its own antiparticle. It is a discrete concentration of energy. It is a massless elementary particle that moves at the speed of light. It has no electric charge 1 and is stable. It is the unit or quantum of electromagnetic radiation or light energy.
Photons are emitted when electrons move from one energy state to another. A photon that is emitted through a biological system is referred to as a biophoton. Fluorescence, for instance, is the absorption and the immediate re-emission of light or photon, which has longer wavelength when re-emitted than that of what was previously absorbed. It occurs as a prior exposure to light and eventually absorbs it then releases it. Similarly, phosphorescence is the emission of light at temperatures below incandescence, as a result of a previous light exposure. The difference is that in phosphorescence, the emission of the photon is delayed. Bioluminescence does emit biophotons. However, it is produced by biochemical means. Therefore, the light emitted is not considered as biophotons.
In terms of photosynthesis, light energy is an important requirement for photosynthesis to occur. The chlorophyll reaction center absorbs photons, and consequently, becomes activated and acts as electron donors.
Symbol: γ
Synonym(s):

  • light quantum

See also:

  • Phosphorescence
  • Osmotrophy
  • Luciferase
  • Count density
  • Fluorescence
  • Electromagnetic radiation
  • P680
  • Related term(s):

    • biophoton
    • Absorptiometry photon
    • Single photon emission computed tomography

    Reference(s):

    1 Kobychev, V.V. and Popov, S.B. (2005). “Constraints on the photon charge from observations of extragalactic sources”. Astronomy Letters. 31 (3): 147–151.


    You will also like...

    Genetics and Evolution
    Genetics and Evolution

    Humans are diploid creatures. This means that for every chromosome in the body, there is another one to match it. Howeve..

    Human gastrointestinal tract
    Human Biology – Food and Digestion

    This tutorial recognizes the importance of food as a source of energy that will fuel many biological processes. A good d..

    Still Water Animals
    Still Water Animals

    Animals living in aquatic habitats have diversified and evolved through time. They eventually occupy ecological niches a..

    Early Earth
    The Origins of Life

    This tutorial digs into the past to investigate the origins of life. The section is split into geological periods in the..

    Biosecurity and Biocontrol
    Biosecurity and Biocontrol

    This lesson explores the impact of biosecurity threats, and why they need to be identified and managed. Examples to incl..

    Hormone Production
    Hormone Production

    Hormones are chemical messengers produced by specialized glands and they were produced by switching on the genes designe..