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Homework Help: Current as a scalar

  1. Jun 27, 2010 #1
    1. The problem statement, all variables and given/known data

    Why has current been defined to be a scalar?


    2. Relevant equations



    3. The attempt at a solution

    No idea whatsoever!
     
  2. jcsd
  3. Jun 27, 2010 #2
    Current density , as you know, is a vector. Current flowing across a fixed piece of surface is the integral of the current density over the surface(=(int)J.dA). Thus,the current is a scalar (but may depend on time).
     
  4. Jun 27, 2010 #3
    Because it is defined as the number of charges moving through the cross-sectional area of the wire per time unit.
     
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