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Wavelength of ejected electrons

  1. Nov 15, 2013 #1
    1. The problem statement, all variables and given/known data

    The threshold frequency of a metal is 3.184 x 10^14 Hz. If a photon of wavelength 368 nm strikes the surface of the metal, what is the wavelength of the ejected electron?

    2. Relevant equations
    f (frequency) = c/(wavelength)
    Eincident = Ethreshold + KE

    3. The attempt at a solution
    Oh man... here it is. I bet I'm missing something huge but it's just been killing me.

    photo 1 copy.jpg

    photo 2 copy.jpg
  2. jcsd
  3. Aug 14, 2017 #2


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    Science Advisor
    Gold Member

    You're good up through the energy calculation. From there you can use:
    $$KE = \frac{p^2}{2m}$$
    to get a value for your momentum. Then just plug that number in to:
    $$\lambda = \frac{h}{p}$$
    and you get your answer.
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