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A problem about blackbody radiation

  1. Jan 31, 2013 #1
    The Stefan–Boltzmann law :
    J = kT^4 where k is Stefan–Boltzmann constant.

    but for non black body ( or grey body)
    the equ becomes
    J = εkT^4
    where 0<ε<1

    can anyone explain y a grey body emit less radiation when compare to the black body at same T? It can found the ans in wiki or the reference book "modern physics"

    thank you
     
  2. jcsd
  3. Jan 31, 2013 #2

    Simon Bridge

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    What is the condition it has to meet to be considered a blackbody? (Why is a blackbody "black"?)

    Compare with grey.
     
  4. Jan 31, 2013 #3
    Black body absorb all incident em wave while grey body absorbs a part of it and reflects the remains
     
  5. Jan 31, 2013 #4

    Simon Bridge

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    Black-body also radiates at the same rate as it absorbs.
    A grey body is just the same as a black-body but it absorbs less energy - therefore it has less energy to radiate.
     
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