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Homework Help: Energy flux in optics in hydrogen gas

  1. Feb 22, 2013 #1
    1. The problem statement, all variables and given/known data
    There is a half space z>0 full with hydrogen gas with density n atoms / metres cube.
    An incident wave plane with pulsation ω coming from z = -∞ arrives at the surface of incidence. This wave transports a flux of energy ∅0 at z=0.
    We consider a elementary cylinder whose axe along z with section S between z and z+dz
    Prove that the flux of energy of the wave is given by d∅/dz= -nσ(ω)∅(z) , σ(ω) is the diffusion cross-section. And therefore ∅(z) = ∅0(z)exp(-z/L).
    I suppose L is the luminance.

    Thank you for your help.

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Feb 22, 2013 #2
    I don't think L is the luminance. Shouldn't it have the same units as z?
  4. Feb 22, 2013 #3
    Yes, of course stupid mistake from me. L has the same dimension as z. But still i have no answer for my question:approve:
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