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Homework Help: What is the work function of the photoelectric material?

  1. May 17, 2017 #1
    1. The problem statement, all variables and given/known data

    Photons with momentum p= 7.88 x 10-18 strike a photoelectric material which is in the configuration shown in the figure. The cutoff voltage is measured to be Vstop= 1.75 V. What is the work function of the photoelectric material?

    2. Relevant equations

    p = Ephoton / c
    E0 = (c ⋅ p) - (Vstop ⋅ e)

    3. The attempt at a solution

    E0 = (3.00 x 108 m/s)(7.88 x 10-18 (ev ⋅ s)/nm) - (1.75 V ⋅ 1.602 x 10-19 J) = 2.36 eV

    Attached Files:

    Last edited: May 17, 2017
  2. jcsd
  3. May 17, 2017 #2
    you should convert the speed of light to nm/s to match the momentum unit (ev.s/nm)
  4. May 17, 2017 #3
    Thanks for catching that error. The new answer I got is 2.36 eV
  5. May 17, 2017 #4
    you are welcome.

    thats still the energy of the photon
    subtract that from the ke
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