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  2. Light-emitting diode - Wikipedia

    en.wikipedia.org/wiki/Light-emitting_diode

    By selection of different semiconductor materials, single-color LEDs can be made that emit light in a narrow band of wavelengths from near-infrared through the visible spectrum and into the ultraviolet range. The required operating voltages of LEDs increase as the emitted wavelengths become shorter (higher energy, red to blue), because of their ...

  3. Light-emitting diode physics - Wikipedia

    en.wikipedia.org/wiki/Light-emitting_diode_physics

    The materials used for the LED have a direct band gap with energies corresponding to near-infrared, visible, or near-ultraviolet light. LED development began with infrared and red devices made with gallium arsenide. Advances in materials science have enabled making devices with ever-shorter wavelengths, emitting light in a variety of colors.

  4. Far-red light - Wikipedia

    en.wikipedia.org/wiki/Far-red_light

    Far-red light is a range of light at the extreme red end of the visible spectrum, just before infrared light. Usually regarded as the region between 700 and 750 nm wavelength , it is dimly visible to human eyes.

  5. Visible spectrum - Wikipedia

    en.wikipedia.org/wiki/Visible_spectrum

    Electromagnetic radiation in this range of wavelengths is called visible light (or simply light). The optical spectrum is sometimes considered to be the same as the visible spectrum, but some authors define the term more broadly, to include the ultraviolet and infrared parts of the electromagnetic spectrum as well, known collectively as optical ...

  6. Red - Wikipedia

    en.wikipedia.org/wiki/Red

    The human eye sees red when it looks at light with a wavelength between approximately 625 and 740 nanometers. [1] It is a primary color in the RGB color model and the light just past this range is called infrared, or below red, and cannot be seen by human eyes, although it can be sensed as heat. [7]

  7. Infrared - Wikipedia

    en.wikipedia.org/wiki/Infrared

    This range of wavelengths corresponds to a frequency range of approximately 430 THz down to 300 GHz. Beyond infrared is the microwave portion of the electromagnetic spectrum . Increasingly, terahertz radiation is counted as part of the microwave band, not infrared, moving the band edge of infrared to 0.1 mm (3 THz).

  8. The LED Hair Regrowth Device That Changed This Editor's ... - AOL

    www.aol.com/led-hair-regrowth-device-changed...

    Powered with 120 red (640 nm) LED wavelengths, designed to target the whole head, you wear the helmet for 10 minutes a day and the light works to increase the flow of blood, oxygen, and nutrients ...

  9. Electromagnetic spectrum - Wikipedia

    en.wikipedia.org/wiki/Electromagnetic_spectrum

    In frequency (and thus energy), UV rays sit between the violet end of the visible spectrum and the X-ray range. The UV wavelength spectrum ranges from 399 nm to 10 nm and is divided into 3 sections: UVA, UVB, and UVC. UV is the lowest energy range energetic enough to ionize atoms, separating electrons from them, and thus causing chemical reactions.