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Homework Help: Photoelectric Effect - Wavelength of a Photon

  1. May 7, 2009 #1
    1. The problem statement, all variables and given/known data
    Calculate the wavelength of a photon having the same momentum as an electron
    moving at 1.0  106 m/s.
    The answer is supposed to be 0.73 nm.

    2. Relevant equations
    Ek = (m*v^2)/2
    Ek = hf - W
    p = E/c = hf/c = h/[tex]\lambda[/tex]

    3. The attempt at a solution
    I first found Ek using the kinetic energy formula, using the speed of the electron given in the question and the mass of the electron.
    I can't quite figure out where to go next.
  2. jcsd
  3. May 7, 2009 #2


    User Avatar
    Homework Helper
    Gold Member

    This problem has nothing to do with the photoelectric effect. Find the momentum of an electron moving at the speed given, substitute it in p = h/λ, and solve for λ.
  4. May 7, 2009 #3
    It is in the photoelectric effect section of the book, though.

    Alright, thanks.
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