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Homework Help: How do you find threshold frequency? (given wavelength and KE of electrons)

  1. Sep 26, 2008 #1
    If you are told that a silver surface is irradiated with light having a wavelength of 230 nm that causes electrons to be ejected with 77.67 kJ/mol of kinetic energy, how would you find the threshold frequency?

    I know that threshold frequency = W / h. W is the work function and h is Planck's constant.

    I seriously don't know where to go from there. Obviously, I would be able to get an answer if I could obtain a value for the work function. However, I don't know what equation would allow me to use the given information (the wavelength and kinetic energy) to find the work function value. If anyone could help me with that, that would be great. Thanks!
  2. jcsd
  3. Sep 26, 2008 #2


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    If 1 mole of electrons has 77.67 kJ of kinetic energy, how much kinetic energy does 1 electron have?

    Also, what's the energy of a photon of wavelength 230 nm?
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