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Photoelectric Effect

  1. Aug 12, 2016 #1
    I have studied photoelectric effect. I have many doubts regarding that, so firstly, I cannot understand when, THRESHOLD FREQUENCY arises. " Threshold frequency is the frequency at which the electron gets ejected from the electrode & runs toward the other negatively charged electrode " , so my question is

    When we are applying energy & we know that the electron will get ejected at Threshold Frequency, then where the left over energy goes???
  2. jcsd
  3. Aug 12, 2016 #2
    At that frequency (red border of photoeffect) of specific material is frequency by which the energy of photon is equal to exiting work of material,in other words electron has to receive at least that amount of energy to relase itself from surface so i think the subject or your interest would be the existing work of material thats the energy the electron loses through his way to relase that surface(electrode) because as einstein showed:Ek= hf-A.
  4. Aug 12, 2016 #3


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    Staff: Mentor

    The "left over" energy goes into the kinetic energy of the ejected electron. If the energy of the photon is only slightly above the threshold energy, the electron will be moving less quickly than if the photon energy is well above the threshhold energy.
  5. Aug 12, 2016 #4
    What about W?
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