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A Question about magnetic flux density B

  1. Apr 27, 2016 #1
    Magnetic flux density B is a vector quantity and thus represents a force. However most texts state that the magnetic force is perpendicular to the direction of B, which is tangential to the magnetic field line at any give point. I assume that this magnetic force refers to the Lorentz force. So my question is:

    1) What exactly does the direction of force B represent?

    2) Would it be correct to state that it is the force B that acts on a test magnet causing it to orient along a magnetic force line?
     
  2. jcsd
  3. Apr 27, 2016 #2

    Dale

    Staff: Mentor

    This is not correct. Not everything that is a vector represents a force. The B field in particular is not a force.
     
  4. Apr 27, 2016 #3
    Yes, I guess that was implied in the first part of the question. So what does the direction of B indicate?
     
  5. Apr 27, 2016 #4

    Dale

    Staff: Mentor

    It is the direction perpendicular to both the magnetic force and the current.
     
  6. Apr 28, 2016 #5
    I've already mentioned that in my question! I wish to know what this "direction" of B represents?
     
  7. Apr 28, 2016 #6

    Dale

    Staff: Mentor

    That is all it represents. There is only one such line which is perpendicular to both the force and the current, and the B field direction identifies it. That is all, there is no more or less meaning.
     
  8. Apr 29, 2016 #7

    Interesting. So, why come up with the concept of direction of the B field at all?

    There must be some reason why a test magnet aligns itself in the direction of the B field....
     
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