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A Effect of visible light on conductivity

  1. Jul 27, 2016 #1
    Are metals better conductors in the presence of visible light? Considering photons in visible spectrum are not energetic enough to induce emission from a metal surface but they do cause the ejection of 'conduction electrons' which are bound to the metal by a few electron volts.
  2. jcsd
  3. Jul 27, 2016 #2


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    No. Metal are substances which have partially filled conduction bands with electrons and the number of electrons is very high, one or two per atom.
    Photoconductivity is observed mostly in semiconductors. Semiconductors have empty conduction band and almost full valence band just around 1 eV below.
    The electrons in the conduction band are coming from either doping or are thermally excited and their number is rather small, one per millions of atoms.
    When you shine light on a semiconductor you excite electrons from the valence to conduction band and the conductivity increases.
  4. Jul 27, 2016 #3
    Good answer, thank you
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