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Modern Physics Photoelectrons

  1. Nov 10, 2008 #1
    Light of 300 nm wavelength strikes a metal plate, and photoelectrons are produced moving as fast of 0.002c. What is the work function of the metal?
     
  2. jcsd
  3. Nov 10, 2008 #2

    hage567

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    What have you tried so far? Please show what work you've done. We don't give out solutions here.
     
  4. Nov 10, 2008 #3
    I don't know what equations to use. Do I have to use the moving speed to find the energy, but I don't know how to use that 300nm since it's not the cutoff wavelength.
     
  5. Nov 10, 2008 #4
    The electrons have an "excess" energy: so the work function should equal the difference between the photon energy and the excess energy.
     
  6. Nov 10, 2008 #5
    Should I use 0.5mv^2=hc/wavelength-work function, then what should I use for the mass in 0.5mv^2, the mass of an electron?
     
  7. Nov 10, 2008 #6

    hage567

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    Yes, you use the mass of an electron.
     
  8. Nov 10, 2008 #7
    So I have 3.108 for the answer of the work function
     
  9. Nov 10, 2008 #8
    is that right?
     
  10. Nov 10, 2008 #9

    hage567

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    Seems reasonable to me.
     
  11. Nov 10, 2008 #10
    Your answer should contain the correct unit, though!
     
  12. Nov 10, 2008 #11
    3.108eV
     
  13. Nov 10, 2008 #12
    okay, that sounds like the right order of magnitude.
     
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