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Direction and magnitude of the current

  1. Nov 7, 2009 #1
    1. The problem statement, all variables and given/known data
    Taking R = 1.00 kΩ and ε = 250 V in the figure, determine the direction and magnitude of the current in the horizontal wire between a and e.
    http://img5.imageshack.us/img5/7250/img001nkm.th.jpg [Broken]


    2. Relevant equations
    Kirchhoff´s law


    3. The attempt at a solution
    I must try to apply Kirchhoff´s loop rule to both rules?
     
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Nov 7, 2009 #2

    Delphi51

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    Homework Helper

    Yes, all three loops. Or perhaps you could combine the 4R and 3R in parallel to get a simpler circuit with only two loops. Once you know I1 and I2, it should be easy to find I in the original circuit.
     
  4. Nov 7, 2009 #3
    I think it will be done with 4R and 3R in parallel. But how can i have the value of the new R?
     
    Last edited: Nov 7, 2009
  5. Nov 8, 2009 #4
    If i have the new value of R i could find I1 and I2, like this:
    (xR)I1+(yR)I2=250
    and
    (xR)I1+(yR)I2=500

    I think it will be the solution, but the problem is that i cant find the new value of x and y if i combine the 4R and 3R in parallel to get a simpler circuit with only two loops.
    Any help? Thanks
     
  6. Nov 8, 2009 #5

    Delphi51

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    Homework Helper

    The 4R and 3R (4000 and 3000 ohms) are in parallel. You must use the formula for the resistance of two resistors in parallel.

    I don't understand what your x and y represent.
    It seems to me the current through the combined resistors would be I1 + I2, so the equations will each have one more term than you have shown.
     
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