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Homework Help: Wheatstone Bridge circuit

  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 14, 2004 #2
    I cannot download the attachment.Fix it pls
     
  4. Nov 14, 2004 #3
    There's not anything he can do, since it's "pending approval"..
     
  5. Nov 15, 2004 #4
    Tis is true only if at BD no current passes. moreover Vad=vdc and Vab=Vbc.
    the special about that is that Iab=Ibc+Ibd and Iad=Idc+Idb. The one red is positive and the other negative.....Since you find the total current that passes through bd you can measure the voltage across it :approve:
     
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