- #1
SUDOnym
- 90
- 1
Hello
I asked a question about infrared and UV a while back for which I got some very informative responses:
https://www.physicsforums.com/showthread.php?t=676881
This is in a sense a very short follow up question: Is the reason that we don't feel 'heat' from an infrared remote control because the intensity of the signal is very weak or because it is at a frequency of infrared that is not sensed by humans as 'heat'?
Additionally, I came across a comment under the article at:
http://www.wisegeek.com/how-does-infrared-heat-work.htm
The comment was:
I don't believe that this is correct - because although the intensity of visible + UV light from the sun is greater than the intensity of infrared, the important point is that it is the amount that these wavelengths are absorved that is important.
It does however raise some questions for me: If the intensity of visible light were high enough, would we feel the same kind of 'heat' as when there is infrared light shone on our skin? (I know that we can get optical lasers that are able to cut through objects due to the amount of energy they deposit in them but could we for example builld an optical laser that deposits just enough energy in the skin that it would feel warm?).
And a related question: UV light in fact does get absorbed by our skin - causing sun tans and (much less desirable!) skin cancer. If we are out on a sunny day, do we feel this UV light as 'heat' on our skin or again is it only the IR in the sun light that causes this sensation?
Thanks
I asked a question about infrared and UV a while back for which I got some very informative responses:
https://www.physicsforums.com/showthread.php?t=676881
This is in a sense a very short follow up question: Is the reason that we don't feel 'heat' from an infrared remote control because the intensity of the signal is very weak or because it is at a frequency of infrared that is not sensed by humans as 'heat'?
Additionally, I came across a comment under the article at:
http://www.wisegeek.com/how-does-infrared-heat-work.htm
The comment was:
Only about 50 percent of the warmth we feel from the sun is due to IR. The other 50 percent is mostly visible and UV.
I don't believe that this is correct - because although the intensity of visible + UV light from the sun is greater than the intensity of infrared, the important point is that it is the amount that these wavelengths are absorved that is important.
It does however raise some questions for me: If the intensity of visible light were high enough, would we feel the same kind of 'heat' as when there is infrared light shone on our skin? (I know that we can get optical lasers that are able to cut through objects due to the amount of energy they deposit in them but could we for example builld an optical laser that deposits just enough energy in the skin that it would feel warm?).
And a related question: UV light in fact does get absorbed by our skin - causing sun tans and (much less desirable!) skin cancer. If we are out on a sunny day, do we feel this UV light as 'heat' on our skin or again is it only the IR in the sun light that causes this sensation?
Thanks