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Homework Help: Circuit with Two Batteries and Six Resistors

  1. Feb 25, 2017 #1
    <Moderator note: Thread moved from technical forums hence no homework template is shown>

    A circuit is constructed with six resistors and two batteries as shown. The battery voltages are V1 = 18 V and V2 = 12 V. The positive terminals are indicated with a + sign, The values for the resistors are: R1 = R5 = 70 Ω, R2 = R6 = 105 Ω R3 = 59 Ω, and R4 = 82 Ω. The positive directions for the currents I1, I2 and I3 are indicated by the directions of the arrows.

    I have gone through the algebra a lot of times, with a lot of different equations. I believe my problem is with my application of the loop rule. Please, point out my mistakes here.

    Equations I came up with:
    1. I2 = I1 + I3
    2. V2 - I2R2 - I1R1 - I6R6 = 0
    3. V2 - I2R2 - I3R3 - V1 - I6R6 = 0
    4. V1 + I3R3 - I1R1 = 0

    Attached Files:

    Last edited by a moderator: Feb 26, 2017
  2. jcsd
  3. Feb 25, 2017 #2


    Staff: Mentor

    What is the current through R5?
  4. Feb 26, 2017 #3


    User Avatar

    Staff: Mentor

    Did you mean R6?

    @PhysicsNo, your loop equations look fine but you've introduced a current I6 that you should be able to write in terms of other, already defined currents. Consider what applying KCL at node a tells you.
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