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How to find max KE of electrons in photoelectric effect

  1. Dec 30, 2011 #1
    The information I'm given is:
    frequency of light: 9X10^14 Hz
    magnitide of VA 1.3 V (not sure what this is, maybe stopping potential?)

    It says to simply state the max KE of the electrons so it must be quite simple but I just don't see it. I tried E=hf but this doesn't give max KE. Must have something to do with the 1.3 V.

    Thanks for your help.
    Last edited: Dec 30, 2011
  2. jcsd
  3. Dec 30, 2011 #2
    Using E = hf gives the energy of an incident photon of radiation. You are on the right track.
    I assume VA (?) is the work function of the metal (expressed in volts) which must be converted to an energy in Joules.
    The work function is energy that must be removed from the incoming photon energy to JUST release electrons, any excess appears as KE of ejected electrons.
    Hope this helps
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