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Homework Help: Photon flux on surface.

  1. Nov 30, 2007 #1
    1. The problem statement, all variables and given/known data
    An area of 2 sq. meter is lit with power 10W/m^2 with light on wave length equal to 600nm.
    What is the photon flux that HIT the 2 sq. meter surface.

    2. Relevant equations
    E=hv - plank const and frequency (c/lambda)
    Photon flux of EMITTED source is flux=N/t=P/hv

    3. The attempt at a solution
    It seems, that somehow the emitted flux P/hv has to be connected with flux that hit the surface...
  2. jcsd
  3. Nov 30, 2007 #2
    It seems that the question is stated in terms of the intensity of light on the surface (a constant 10W/(m^2) - note that this is INTENSITY, not power). In this case there is no need to calculate the intensity of light falling on the surface from the power of the source - it is given in the question. In that case, it is simply a matter of finding the number of photons in the 20 Joules that reach the surface each second from the Planck's constant relation given, E=hc/l.
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