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Homework Help: How to solve this circuit problem

  1. Nov 13, 2004 #1
    How do i solve this? I wasn't given any examples at all. But i've tried to do this.

    Iab + Iad = Ibc + Idc <--------- they have to or else Kirchoff's law violated.

    so Vab = Vad but i'm not sure if Vbc = Vdc?
    i'll continue assuming Vbc = Vdc

    Vab/40 + Vad/20 = Vbc/70 + Vdc/50

    Va=0.45714286 Vc

    Vbd/60+ Vc/50 = Va/20

    Vbd = 0.1714286Vc

    i thought that Va + Vc + Vbd = 20

    solved for Vc and i got Vbd as 2.105263 V

    The answer is 0.94V. Obviously i got something wrong here. Can some one explain to me where I went wrong, and how i can fix this. Thanks

    Attached Files:

  2. jcsd
  3. Nov 13, 2004 #2
    Your problem is you continue to asume that Vbc=Vdc, that lead you to the wrong answer.
    First, you should find the current for the whole circuits, you can divide the circuits into parts .Then you can find the pottential of each part, then you can find the current of each resistance, then you subtract them to find the dirrection of the current through Rbd. Be careful at the last part.
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