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Infrared heats a body but UV heats less

  1. Apr 3, 2012 #1
    Infrared heats a body but UV heats less!!

    If we consider two bodies of indentical properties (and temperature) and we apply radiation on them with different EM wave ,One with Infrared and the other with UV ray,we find that the body exposed by IR has more temperature increase with respect to other.....
    The Problem is UV has higher freqency and thus have more energy having same intensity ,so it should heat more.
     
  2. jcsd
  3. Apr 3, 2012 #2
    Re: Infrared heats a body but UV heats less!!

    IR heats. UV burns.
     
  4. Apr 3, 2012 #3

    mfb

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    Re: Infrared heats a body but UV heats less!!

    With the same intensity, the UV light has fewer photons, as the energy per photon is higher and intensity is usually defined as energy per time per area.

    Without any knowledge about your body, it is impossible to say which photons heat it more.
     
  5. Apr 3, 2012 #4
    Re: Infrared heats a body but UV heats less!!

    Same intensity =/= same number of photons. Same intensity = same total energy.

    So, your body absorbs IR more than UV, and thus is heated more by the IR than the UV. There is no issue here.

    (If, on the other hand, it absorbed more UV than IR, it would be heated more by the UV.)
     
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