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Solving Circuits with R, I, V.

  1. Jul 22, 2012 #1
    1. The problem statement, all variables and given/known data

    Linked below is a rough picture of the circuit for which I need to find the currents.

    https://docs.google.com/drawings/pub?id=1jY6r1yjOf9OG5VixjZKcQbG2rj-ZQ7LZzaybGzkjva0&w=960&h=720

    2. Relevant equations

    Kichhoff's Laws, Ohm's Law.

    3. The attempt at a solution

    I'm doing a self-study using a book that I think may be riddled with errata, so I keep finding that I'm getting a result which disagrees with the answer the back and cannot see why my answer differs. I get the system of equations

    [itex]11 - 3i_{3} + 1 = 0[/itex]

    [itex]11 + 6i_{2} = 0 [/itex]

    [itex]-3i_{3} + 1 -6i_{2} = 0[/itex]

    [itex] i_{3}=i_{1}+i_{2}[/itex]

    I believe my choice of direction of flow is consistent and cannot affect my solution up to a change of sign. The book produces the result that [itex]i_{2}=13/6[/itex] when I obtain 11/6.
     
  2. jcsd
  3. Jul 22, 2012 #2

    SammyS

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    attachment.php?attachmentid=49266&stc=1&d=1342999707.png
    Added in Edit:

    If i2 = 11/6 A, then the voltage drop across the 6Ω resistor is 11 V, which makes perfect sense. So, it looks like you are correct !
     

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    Last edited: Jul 22, 2012
  4. Jul 23, 2012 #3

    CWatters

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    I agree. The voltage across the 6 ohm resistor is fixed at 11V so the current is simply 11/6 amps.

    Have they/you labelled the currents correctly?
     
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