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Questions tagged [uv]

Non-visible light with a higher energy and shorter wavelength than violet light, UV is notable for its ability to cause DNA damage.

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Is it possible to see the germs on your hand without being in the dark or using a microscope?

I know that black light is often used to see the germs on people's hands but is their anyway we can examine the germs on people's hands without having the surroundings be completely dark (what is ...
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11 views

Effects of uv-c 280nm 1.200uW-sec LED radiation on water?

I recently ordered a LARQ bottle. It's a drinking bottle for water that is equipped with a UV-C LED 280nm in the cap. It switched on every 2 hours and thus purifies the water. It provides a 1.200uW-...
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115 views

Could being exposed to excess UV in the arctic lead to a human eye color change? If so, what is the mechanism?

The CBS News article Expedition Antarctica: A father and son's journey to save the planet says (in part): Thirty-two years ago, Robert Swan made history as the first person to walk to both poles. ...
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31 views

UV-lamp, DNA and RNA extraction lab

I'm equipping a lab room (~3x5 meters) that's supposed to be used for DNA and RNA extractions. I know about the basic safety precautions when working with RNA and DNA extraction (fresh gloves, ...
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1answer
437 views

Why does UVA penetrate deeper than UVB, though it's weaker?

Even though UVA radiation ranges in longer wavelengths (315–400 nm) than UVB (280–315 nm) and thus is less energetic, UVA is able to penetrate deeper into the skin and even reach the dermis. Why is ...
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2answers
144 views

If my sunglasses provide “100% UVA/UVB Protection” why can't look directly at the sun?

Is it simply the amount of visible light entering the eye? I'm simply confused as to why experts say that sunglasses do not provide adequate protection when they are advertised as blocking 100% of the ...
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2answers
485 views

Why do redheads tend to sunburn more easily?

Reading Marion Roach's book on redheads she mentions visiting Rees lab where he shines UV light on her skin. Apparently this is an ongoing experiment of his regarding the propensity of redheads to ...
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1answer
101 views

Using UV to kill bacteria in shoes

I see that UV-C is the best to kill bacteria generally. We are interested in using to kill off odor in shoes. What illuminance is needed to kill most bacteria with UV-C? Thanks!
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37 views

Influence of artificial sunlight on the human body

In a hypothetical scenario, where a large, permanently manned craft is in a continual orbit, and natural sunlight cannot be used as the craft may keep moving and turning, artificial sunlight is used ...
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1answer
951 views

Is it safe to look indirectly at the Sun?

I.e., is exposure of sunlight onto the peripheral vision less damaging than exposure onto the fovea?
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1answer
298 views

Will an 11W UVC lamp kill bacteria?

If I shone a UVC lamp (11W) on something (say for example a plastic phone case) for an hour, would that kill off a noticeable amount of bacteria? That is, if I were to go over the case with a cotton ...
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1answer
3k views

Does every wave length of UV kill bacteria?

Will every wave length of UV work for killing bacteria? So will UV A, UV B and UV C all work? Or will only the shortest of the three, UV C, work? Also, will the average UV lamp help against bacterial ...
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58 views

How much time is required between repeated exposures to sun to prevent sunburn [closed]

After being in the sun, how much 'rest' is required before you can expose yourself again? e.g. from Wikipedia: Sunburn can occur in less than 15 minutes So if you were in a place where sunburn ...
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1answer
179 views

Detecting UV by humans

From my experience humans can detect UV - not by seeing it but by pain in their eyes. Many people (me too) feel pain when looking at UV lamps. When looking at sun through clouds I still can feel pain ...
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1answer
242 views

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 ...