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Homework Help: Unbalanced Scheering Bridge and Thevenin

  1. Jul 19, 2010 #1
    1. The problem statement, all variables and given/known data

    Find the magnitude and phase of the current flowing through the galvanometer whose internal resistance is negligible.C1=C, C2=0, Cx=2C, R2=R3=R, Rx=0

    http://www.freeimagehosting.net/uploads/4ce4800510.png

    3. The attempt at a solution

    Magnitude of the current:

    Using the Thevenin equivalent circuit,


    Z1 = 1/jwC1 = 1/jwC
    Z2 = R2 || 1/jwC2 = R
    Zx = Rx + 1/jwCx = 1/jw2C
    Z3 = R3 = R

    Rth = (Z1 || Z2) + (Zx || Z3)
    Vth = V from c to b = Vc - Vb = Vac - Vab = E (Z1/(Z1+Z2) - Zx/(Zx+Z3))
    Ig = Vth/Rth

    Would this be correct?

    Have no idea on how to get the phase of the current....

    Thanks!
     
  2. jcsd
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