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UV-B lamps are lamps that emit a spectrum of ultraviolet light with wavelengths ranging from 290–320 nanometers. This spectrum is also commonly called the biological spectrum due to the human body's sensitivity to light of such a wavelength. [1] UV-B light does not tan the skin very much, compared to the UV-A lamps that are used in tanning beds.
Full-spectrum light is light that covers the electromagnetic spectrum from infrared to near-ultraviolet, or all wavelengths that are useful to plant or animal life; in particular, sunlight is considered full spectrum, even though the solar spectral distribution reaching Earth changes with time of day, latitude, and atmospheric conditions.
The light that excites the human visual system is a very small portion of the electromagnetic spectrum. A rainbow shows the optical (visible) part of the electromagnetic spectrum; infrared (if it could be seen) would be located just beyond the red side of the rainbow whilst ultraviolet would appear just beyond the opposite violet end.
While allowing UV light to reach the retina can lead to retinal damage, the short lifespan of mice compared with other mammals may minimize this disadvantage relative to the advantage of UV vision. [31] Dogs have two cone opsins at 429 nm and 555 nm, so see almost the entire visible spectrum of humans, despite being dichromatic. [32]
Artificial sunlight is useful in treating and preventing seasonal affective disorder (also known as winter depression, which causes depression symptoms specifically in winter), [3] and delayed sleep phase syndrome, in which the circadian rhythm (the rhythmic alternation between daylight and nighttime behavior and bodily states) is disturbed and the person falls asleep much later than he or she ...
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 .
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The U.S. Environmental Protection Agency (EPA) published UV dosage guidelines for water treatment applications in 1986. [77] It is difficult to measure UV dose directly but it can also be estimated from: Flow rate (contact time) Transmittance (light reaching the target) Turbidity (cloudiness) Lamp age or fouling or outages (reduction in UV ...