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Homework Help: Maxwell's equations

  1. Aug 14, 2011 #1

    Why is eqn 34.16
    B(x,t)•l - B(x+dx,t)•l instead of
    B(x+dx,t)•l - B(x,t)•l ?
  2. jcsd
  3. Aug 14, 2011 #2


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    The line integration is being followed around the rectangle counter-clockwise, so the segment along which the magnetic field is B is parallel to the direction of integration, while the segment with ( B + dB ) is anti-parallel to the integration direction.
  4. Aug 14, 2011 #3

    I like Serena

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    Hi again sparkle123! :smile:

    It's a matter of convention: one of the many applications of the right hand rule.
    Point your thumb in the direction of the positive y-axis, and your fingers give the direction that is by convention positive.
    This is shown by the arrowheads in the loop.

    So B(x,t) is taken as positive, while B(x+dx,t) is taken as negative.

    Edit: overtaken by dynamicsolo. ;)
  5. Aug 16, 2011 #4
    Thanks dynamicsolo and I like Serena!! :)
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