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Basic Circuit, Kirchoff's Rules

  1. Feb 14, 2009 #1
    1. The problem statement, all variables and given/known data
    Using Kirchhoff's rules, find the currents I1, I2, and I3 in the circuit shown where R1 = 8.0 ohms, R2 = 9.0 ohms, and R3 = 5.0 ohms.
    ae21-9.gif


    2. Relevant equations
    Loop law, Junction law


    3. The attempt at a solution
    I know how to work the formulas, but the picture is really confusing. The directions of the currents don't make any sense. I have arrows going away from both the positive and negative terminal and I can't figure out how to set up the equations with the arrows like that.
     

    Attached Files:

  2. jcsd
  3. Feb 14, 2009 #2

    Hootenanny

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    The first thing you need to do is choose a direction which you will take as positive, either clockwise or anti-clockwise. Once you have chosen your convention make sure you stick to it. Then just start applying Kirchoff's laws to the loops and junctions taking care to stick to the convention you defined at the start.
     
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