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Homework Help: Super Node Analysis

  1. Oct 2, 2015 #1
    1. The problem statement, all variables and given/known data
    Find V1,V2,V3,I1,I2,I3
    2. Relevant equations

    3. The attempt at a solution
    Analysis at super node:
    V3-V1=40 (equation 1)

    2V1 - 3V2 +2V3 = 0
    After substituting in equation 1:
    4V1-3V2 = -80

    Analysis at V2

    After substituting in equation 1:
    -3V1+5V2 = 80

    But I think I'm doing something wrong, I don't feel like the voltages should be zero...

    Attached Files:

  2. jcsd
  3. Oct 2, 2015 #2


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    Staff: Mentor

    For your supernode equation, you left out the term for the 20 Ω resistor between V3 and the reference node.

  4. Oct 3, 2015 #3
    Oh ok, I fixed that part and now I have these equations:

    6V1-3V2=-160 and -3V1+5V2=80

    When I solve for V2, I get zero. And for V1 I get -26.7. Is it ok for one of the voltages to be zero?
  5. Oct 3, 2015 #4


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    Staff: Mentor

    I question the sign of your V1. Since it's directly connected to the + terminal of the only voltage source I would expect it to have a positive potential. Check your math.

    Zero is a perfectly good value for a potential for V2. In fact, it looks correct to me :smile:
  6. Oct 3, 2015 #5
    Thanks so much!! :)
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