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Photoelectric effect+frequencies

  1. Apr 24, 2009 #1
    does anyone know what the minimum frequency actually is that the light needs to be in order for photons to be emmited? also, is there a point where if the frequencies too high, does THAT = no electron emmision? that is all!
     
  2. jcsd
  3. Apr 24, 2009 #2
    I think that there are some photocathodes that work up to about 650 nanometers wavelength for photoelectrons to be emitted. Using 300 meters = 1 MHz as a conversion, 650 nanometers converts to 4.6 x 1014 Hz.
    The photoelectric effect is important up to photon energies of about 100 keV, the binding energy of k-shell (1S) electrons in the heaviest nuclei. Using 1 eV= 1240 nm = 2.4 x 1014 Hz, 100 kHz corresponds to 2.4 x 1019 Hz.
     
  4. Apr 24, 2009 #3
    oh so theres a bunch of electricity involved huh. are hertz how many times the photon zigzags per second?
     
  5. Apr 24, 2009 #4

    ZapperZ

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    There is a problem in the very basic understanding of the photoelectric effect here. Maybe you should start with the basic Einstein's photoelectric effect equation, and then see if there is still something you don't understand.

    http://galileo.phys.virginia.edu/classes/252/photoelectric_effect.html

    In particular, pay attention to what is meant by the work function that is material dependent.

    Zz.
     
  6. Apr 24, 2009 #5

    i dont understand this part at all. why is it that when theres less light, this = less electrons? less light would mean that less electrons would be knocked off. which would mean that the charge would maintain itself in the dark. this is backwards and doesnt make sense. why is it that the electric charge decreases i nthe dark box, when light, removes electrons? ???????????????????????? feel free to jump in and answer this if you know the answer i dont get it AT ALL!
     
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