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Homework Help: Junction Rule

  1. Sep 24, 2006 #1
    http://online.physics.uiuc.edu/courses/phys102/fall06/print_files/lect06_handout.ppt#10 [Broken]

    Slide 10

    How come the sign for R3 is not the opposite, shouldnt the postive charge be carried from E2 up to R3 making it + then -
    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. Sep 25, 2006 #2


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    The way the currents are written, I1 + I2 = I3. If E2 is sufficiently strong, the current I3 may be negative, indicating it is in the opposite direction as that which is written.

    If anything the current I2 should have been written in the opposite direction and it's polarity reversed, such that I1 = I2 + I3. By convention, currents are usually written in the clockwise direction of a loop. The + sign simply indicates a higher potential.
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