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Electron flow

  1. Jan 7, 2012 #1
    What is the speed of electron flow in an eletric curcuit? A battery (cell) with a copper wire shorted across the positive and negative posts. What will the electron flow be through the copper wire?
     
  2. jcsd
  3. Jan 7, 2012 #2
  4. Jan 7, 2012 #3
    Each individual electron moves very slowly for example in a copper wire of radius 1 mm carrying a steady current of 10 Amps, the drift velocity is only about 0.024 cm/sec.

    However because there are electrons throughout the whole length of the copper wire, its a bit like pushing on the end of a pipe full of putty, the putty at the opposite end starts to move even though your end hasn't moved very far.
     
  5. Jan 7, 2012 #4
    does the speed change? or is it constant? for instance does the speed of I depend on its volume which would in turn be dependant on E or R ?
     
  6. Jan 7, 2012 #5
    [itex] I = nAvQ[/itex]

    Where,

    I = electric current
    n= charged particles per unit volume
    A= cross sectional area of conductor
    v= drift velocity
    Q= charge of each particle

    so therefore

    [itex] v = \frac{I}{nAQ} [/itex]
     
  7. Jan 7, 2012 #6
    Thank you for your help. Ive been imersed in labor these past 40 years having to set aside some of the questions Ive had since childhood. I thank you for clearing this one up. My electronics instructor years ago said the electrons in a cucuit moved at the speed of light, which I always questioned, because of mass issues, Now I know. thanks again.
     
  8. Jan 7, 2012 #7

    http://www.jimloy.com/physics/electric.htm [Broken]

    This article should explain it a bit better than I did.
     
    Last edited by a moderator: May 5, 2017
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