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Homework Help: Using the Loop rule to find potential Difference

  1. Oct 13, 2012 #1
    1. The problem statement, all variables and given/known data

    Find the potential difference between points a and b.

    Picture of Circuit involved.

    2. Relevant equations


    3. The attempt at a solution

    Pretty much completely lost, due to the only one current shown I'm not sure which way the current flows through the rest of the circuit so I do not know how to go about the loop rule.
    It started off kinda like

    -I1(30Ω)=2.118 V

    But I know that cannot be correct cause if you left from the 24V battery and went down you'd have something about 23.3V across there, like I said, completely lost, any help would be great.
  2. jcsd
  3. Oct 13, 2012 #2
  4. Oct 13, 2012 #3
    This is useful, in a case like mine you wouldn't want multiple I notations of current cause then your introducing variables you don't know right?
    should I go opposite the current from b→a?

    Since that is the only value of I given?
  5. Oct 14, 2012 #4
    Using the one know current, the current would be the same at a correct?
    If so you couls just do

    Which implies

    Or is this still the wrong path?
    Do I need to use loop rules and find the unknown values of the current when it splits?
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