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Photons and the Photoelectric effect

  1. Feb 13, 2007 #1
    1. The problem statement, all variables and given/known data

    Light is incident on the surface of metallic sodium, whose work function is 2.3 eV. The maximum speed of the photoelectrons emitted by the surface is 1.08 106 m/s. What is the wavelength of the light?

    2. Relevant equations



    3. The attempt at a solution

    None so far
  2. jcsd
  3. Feb 13, 2007 #2


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    What is the kinetic energy imparted to the electron and thus what was the total energy of the photon.
  4. Feb 13, 2007 #3
    Could you be a bit more specific?
  5. Feb 13, 2007 #4


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    Well you know the photon energy is the energy needed to remove the electron plus the kinetic energy of the emited electron. You are given the work function (i.e. the energy required to remove the electron) and the electron speed from which you can work out the kinetic energy of the electron. You have already stated the relation between photon energy and frequency. What is the relationship between frequency and wavelength of light?
  6. Feb 13, 2007 #5
    So I use .5mv^2 to get the KE.
    From there I divide the sum of the KE and work function by Planck's Constant. I then divide c by f to get the wavelength?
  7. Feb 13, 2007 #6
    Ok, I got it. I made the problem more difficult than it needed to be. Thank you for the help.
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