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Circuit Segment (Two sources with a resistor in between)

  1. Oct 7, 2014 #1
    1. The problem statement, all variables and given/known data
    If a current I=4 A exists between points a and b, R1=6 [PLAIN]http://loncapa.mines.edu/adm/jsMath/fonts/cmr10/alpha/100/char0A.png, [Broken] R2=6 [PLAIN]http://loncapa.mines.edu/adm/jsMath/fonts/cmr10/alpha/100/char0A.png, [Broken] V1=16 V, and V2=6 V,the voltage difference Va−Vb is


    2. Relevant equations
    V=IR

    3. The attempt at a solution
    Well, I do V=IR for the first section up to source V1 (so V=4(6)), but once I get in between, I don't know how to deal with the inside having two voltage sources bombarding it. The answer is 58 V (it's multiple choice), but how?
     

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    Last edited by a moderator: May 7, 2017
  2. jcsd
  3. Oct 7, 2014 #2

    td21

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    Gold Member

    From the answer, you can guess the physics. Hint: 24 + 24 + x = 58?
    What does the value of x imply the direction of the potential difference caused by the voltage sources?
     
  4. Oct 7, 2014 #3

    gneill

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    Staff: Mentor

    You have the current and its direction. So you can assign potential drops across the resistors. Pencil them in on your diagram. Then do a "KVL walk" from b to a summing up the potential changes as you go.
     
  5. Oct 7, 2014 #4
    There we go! I thought you had to do something with the two sources going towards the resistor.

    I just went from A to B doing Kirchoff Law calcs (so going in the direction of the current was a negative, going from positive to negative terminals was negative, and the reverses were positive) and am getting it now. Thank ya!
     
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