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Homework Help: Electron Drift Velocity in Semiconductors

  1. Apr 1, 2015 #1
    1. The problem statement, all variables and given/known data
    "The low [electron] density of a semiconductor means that the conduction electrons travel much faster than they do in conductors."

    In order to fully understand this, I feel that I need to know why this occurs.

    2. Relevant equations
    I = nAve

    I = current
    n = electron density
    v = average drift velocity
    e = charge on one electron

    3. The attempt at a solution
    I know that, mathematically, the electrons need to travel faster in order for the current to be maintained, since current is flow of charge per unit time. I understand from the equation why this is the case, and the numbers make sense. However, I can't understand why the electrons would move faster just because there are fewer of them, and why the current doesn't just fall when a semiconductor is inserted into a circuit.
  2. jcsd
  3. Apr 1, 2015 #2
    Totally guessing here, but perhaps you have the same amount of EMF distributed among fewer electrons, resulting in a higher speed for each electron?
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