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  2. Visible spectrum - Wikipedia

    en.wikipedia.org/wiki/Visible_spectrum

    The visible spectrum is defined as that visible to humans, but the variance between species is large. Not only can cone opsins be spectrally shifted to alter the visible range, but vertebrates with 4 cones (tetrachromatic) or 2 cones (dichromatic) relative to humans' 3 (trichromatic) will also tend to have a wider or narrower visible spectrum ...

  3. Electromagnetic spectrum - Wikipedia

    en.wikipedia.org/wiki/Electromagnetic_spectrum

    By definition, visible light is the part of the EM spectrum the human eye is the most sensitive to. Visible light (and near-infrared light) is typically absorbed and emitted by electrons in molecules and atoms that move from one energy level to another. This action allows the chemical mechanisms that underlie human vision and plant ...

  4. Absorption (electromagnetic radiation) - Wikipedia

    en.wikipedia.org/wiki/Absorption_(electromagnetic...

    By recording the attenuation of light for various wavelengths, an absorption spectrum can be obtained. In physics, absorption of electromagnetic radiation is how matter (typically electrons bound in atoms) takes up a photon's energy—and so transforms electromagnetic energy into internal energy of the absorber (for example, thermal energy). [1]

  5. Radiation - Wikipedia

    en.wikipedia.org/wiki/Radiation

    Light, or visible light, is a very narrow range of electromagnetic radiation of a wavelength that is visible to the human eye, or 380–750 nm which equates to a frequency range of 790 to 400 THz respectively. [4] More broadly, physicists use the term "light" to mean electromagnetic radiation of all wavelengths, whether visible or not.

  6. Light - Wikipedia

    en.wikipedia.org/wiki/Light

    Light, visible light, or visible radiation is electromagnetic radiation that can be perceived by the human eye. [1] Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 terahertz .

  7. Spectrum (physical sciences) - Wikipedia

    en.wikipedia.org/wiki/Spectrum_(physical_sciences)

    The visible spectrum is the part of the electromagnetic spectrum that can be seen by the human eye. The wavelength of visible light ranges from 390 to 700 nm . [ 4 ] The absorption spectrum of a chemical element or chemical compound is the spectrum of frequencies or wavelengths of incident radiation that are absorbed by the compound due to ...

  8. Cardiac pacemaker - Wikipedia

    en.wikipedia.org/wiki/Cardiac_pacemaker

    An artificial cardiac pacemaker (or artificial pacemaker, so as not to be confused with the natural cardiac pacemaker) or just pacemaker is an implanted medical device that generates electrical impulses delivered by electrodes to the chambers of the heart either the upper atria, or lower ventricles to cause the targeted chambers to contract and ...

  9. Light effects on circadian rhythm - Wikipedia

    en.wikipedia.org/wiki/Light_effects_on_circadian...

    Humans are sensitive to light with a short wavelength. Specifically, melanopsin is sensitive to blue light with a wavelength of approximately 480 nm. [ 19 ] The effect this wavelength of light has on melanopsin leads to physiological responses such as the suppression of melatonin production, increased alertness, and alterations to the circadian ...