Electromagnetic radiation, specifically the range of frequencies visible to humans ("visible light").

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What is the chemical process involved in human hairs changing colour after sun exposure?

After a day at the beach, my skin tans due to Melanin. But I also observe the black hairs on my arm turn a blond colour. My question is What is the chemical process involved in human hairs ...
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18 views

Are insects attracted to near infrared light?

Do insects see near infrared light? If yes, are they attracted to it at night, as they are to visible light sources? I am building something similar to a home-made trailcam with a Raspberry Pi ...
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What is the PAR (photosynthetically active radiation) curve, numerically speaking?

I'm trying to do some rough figuring to calculating efficiencies of various light sources for growing plants. I'm hampered, however, by the lack of a curve to multiply by the spectrum of light ...
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75 views

Is light required for seed germination?

Is light required for germination of every seed? If not, why don't some plants require it? Is there any difference in the quality and duration of light required ? It would be interesting if someone ...
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189 views

Is it safe to look at infrared LEDs?

What happens if one looks directly at infrared LEDs? Sometimes I see this kind of LED at night as red dots and I'm also courious about it. I was wondering what would happened if one looked directly ...
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What causes a selective shift of colour perception after removing wavelength filtered glasses?

Background To improve sleep by reducing blue-light melatonin disruption, I wear night-glasses that filter short wavelengths (e.g. something like these). With these glasses on, both the top and bottom ...
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Does bright environment strain eyes more than dim?

I'm trying to figure out how to modify my working conditions so that I can program longer without harming my eyes. Because doing so experimentally hasn't given conclusive results so far, I decided to ...
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Are there specific conditions that allow humans to see ultraviolet wavelengths

It is fairly common knowledge that the lens in its normal state absorbs ultraviolet (UV) radiation. An interesting notion has come up from time to time in my reading that suggests there are a small ...
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Do non-green flower colors have any functional interactions with the sun?

I always hear the pseudo-evolutionary claim "plants are green because they need to use red and blue light". If this premise to my question is true, What (if any) other functional relationship occur ...
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Does artificial high intensity light damage permanently dark ecosystems?

Popular science features on wildlife typically capture camera images using natural light, or high-speed exposures. This is not possible where the ambient light is extremely poor. E.g. Caves, Undersea ...