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Biot-savart law

  1. Jul 21, 2012 #1
    Why is there no equation for solving for the magnetic field produced by multiple charges in free space? To solve for this do you sum up all the magnetic fields produced by each of the point charges or what?
  2. jcsd
  3. Jul 21, 2012 #2


    Staff: Mentor

    That is correct. Maxwell's equations are linear, which means that the field produced by two point charges is just the sum of the fields from each individual charge.
  4. Jul 22, 2012 #3
    Yes, if you add the magnetic fields up with a retardation factor. Changes in the magnetic field propagate at the speed of light. Therefore, changes in the electric current are retarded in the sense of having a delay.
    For small regions, the time delay is negligible.
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