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  2. Visible spectrum - Wikipedia

    en.wikipedia.org/wiki/Visible_spectrum

    White light is dispersed by a glass prism into the colors of the visible spectrum. The visible spectrum is the band of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called visible light (or simply light).

  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. Artificial cardiac pacemaker - Wikipedia

    en.wikipedia.org/wiki/Artificial_cardiac_pacemaker

    Biventricular pacemaker. This pacemaker has three wires placed in three chambers of the heart. One in the atrium and two in either ventricle. It is more complicated to implant. [10] Rate-responsive pacemaker. This pacemaker has sensors that detect changes in the patient's physical activity and automatically adjust the pacing rate to fulfill the ...

  5. Electromagnetic radiation - Wikipedia

    en.wikipedia.org/wiki/Electromagnetic_radiation

    Since the energy levels of electrons in atoms are discrete, each element and each molecule emits and absorbs its own characteristic frequencies. Immediate photon emission is called fluorescence, a type of photoluminescence. An example is visible light emitted from fluorescent paints, in response to ultraviolet . Many other fluorescent emissions ...

  6. 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.

  7. 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 ...

  8. Non-ionizing radiation - Wikipedia

    en.wikipedia.org/wiki/Non-ionizing_radiation

    IR wavelengths are longer than that of visible light, but shorter than that of terahertz radiation microwaves. Bright sunlight provides an irradiance of just over 1 kilowatt per square meter at sea level. Of this energy, 527 watts is infrared radiation, 445 watts is visible light, and 32 watts is ultraviolet radiation. [7]

  9. 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 .