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Homework Help: Calculating the Current in a Two battery Combination Circuit

  1. Feb 27, 2012 #1
    1. The problem statement, all variables and given/known data

    For the circuit shown in the figure below, calculate the current I4 through the 1.94Ω resistor.
    cutj20104.gif
    As shown, R1 = 4.05Ω, R2 = 8.11Ω, R3 = 6.17Ω, R4 = 1.94Ω, I1 = 2.97A and E1 = 12V

    2. Relevant equations
    V=IR
    ƩI in a junction = ƩI out of a junction
    ƩV in a loop = 0

    3. The attempt at a solution
    I1R1+I1R2 -E1 + I2R3 =0
    I1 = I2 + I4
    So
    I4 =I1 - ((-(I1*R1) - I1R2 + E1)/R3)

    I don't have many tries left, so I want to know if my analytical solution is correct, and if I've just been making my error plugging the numbers back in.
     
  2. jcsd
  3. Feb 27, 2012 #2

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    Hi BornSurvivor! :smile:
    looks ok so far

    but won't you need an equation involving E2 ? :confused:
     
  4. Feb 27, 2012 #3
    Nope! Those two equations were all I needed. It turns out I had mixed up the numbers for R2 and R3. :)
     
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