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What does current density mean?

  1. Apr 8, 2016 #1
    1. The problem statement, all variables and given/known data
    Current density is the amount of current per cross sectional of flow. I'm having trouble wrapping my head around this definition. Surface charge or volume charge I understand better since they are almost analogous to the density we all understand (amount of matter/charge per unit area/volume/length). Current is something that's moving and its a little harder for my intuition to understand this. Could anyone please give any examples or anything to understand this concept better?

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Apr 8, 2016 #2
    while doing some reading, I have though of another question, I see a lot of discussion about currents having with time. That seems all well but is there also such thing as a current changing in position? I was thinking if the wire was not uniform like the radius changes.
  4. Apr 9, 2016 #3


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    Homework Helper

    The current is the whole charge flowing through a cross-section of a wire or any conductor in unit time. The current density is the current crossing perpendicularly a unit area in unit time. The current density is a vector, it has direction in addition to magnitude, and it can depend on place.
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