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Homework Help: Photoelectric effect classical approach

  1. Apr 28, 2009 #1
    1. The problem statement, all variables and given/known data
    Assume that a point source of light gives 3 watt = 3 J/s of light energy.

    a) assume uniform radiation in all dirrections, find the light intensity in ev/m2*s
    b)Assuming some reasonable size for an atom, **** the energy/time incident on the atom for this intensity.

    2. Relevant equations

    resonable atom size = 10-10m
    I = E/(area*t)

    3. The attempt at a solution

    a) I think I got this one correct, however I'm not sure. Here is what I did:
    I=E/(area*time) = ((3J/s)*(6.24x1018 ev/J))/(4 m2*s)
    = 4.68X1018 ev/m^2*s

    b) I have no idea what to do with this. I was thinking maybe find the surface area of the atom and divide that by the intensity? which would lead to (10-20)/4.68X1018 ev/m^2*s
    Last edited: Apr 28, 2009
  2. jcsd
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