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So, my doubt is actually very simple. I've been studying about electromagnetic waves, and I read that IR waves are commonly called heat waves, meaning that they actually make us physiologically feel the heat. My question is: why do larger wavelengths do not easily cross through matter allowing easier absorption, while shorter ones do?

Italo Marinho
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  • This might be worth a good read: https://www.livescience.com/50260-infrared-radiation.html#:~:text=Infrared%20radiation%20(IR)%2C%20or,are%20the%20sun%20and%20fire. – Gert Feb 04 '21 at 19:33
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    Re, "I read that IR waves are commonly called heat." Just because it's in print, that doesn't make it true. All wavelengths of electromagnetic radiation will heat up an object that absorbs them. My guess is, there aren't many things that radiate enough energy to make you feel toasty warm that won't also kill you or blind you or give you cancer, etc. Maybe a better question is, why do all of the "safe" ones radiate most of their energy in long IR wavelengths? Why is 10,000W of long-wave IR on your skin safer than 10,000W of radio waves, or 10,000W of X-Rays? – Solomon Slow Feb 04 '21 at 20:40
  • Check out this site for the interaction of radiation with matter. http://hyperphysics.phy-astr.gsu.edu/hbase/mod3.html – Bob D Feb 04 '21 at 20:41
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    Related: https://physics.stackexchange.com/questions/80983/how-does-infrared-relate-to-heat. Answer suggests that IR is special because it is compatible with vibrational transitional energies of molecules. – jpf Feb 04 '21 at 21:04

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