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Free electrons at zero kelvin?

  1. Jul 12, 2012 #1
    At zero kelvin,are there free electrons?

    At zero kelvin,the free electrons should have ZERO energy.But they are able to move under the influence of a electric field?
    But when they are attracted towards the positive potential shouldn't they gain K.E? So they are moving at zero kelvin?
  2. jcsd
  3. Jul 12, 2012 #2
    you cannot send fermions at such temperature (they won't ever reach 0 K), just because they are fermions and must obey Pauli's exclusion principle they will have energy from that...
  4. Jul 12, 2012 #3


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    Zero temperature just means that all particles reach the lowest-possible states. In terms of fermions, they still have energy compared to the ground-state, but this energy does not contribute to temperature.
    Note that this definition does not include any "velocity". You can have a collection of electrons at (close to) zero temperature, moving in one direction in your lab.
  5. Jul 12, 2012 #4


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    I do not understand your issue here. By definition, free electrons as .... FREE! If they are attracted to a "positive potential", then they are NOT free electrons in the first place!

    So are they free, or aren't they? And where are these "free electrons" that you are considering? A metal? A metal's band structure is often calculated at 0 K! So the conduction electrons are in the conduction band at 0 K! They are free to move!

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