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Nodal Voltage analysis

  1. Feb 1, 2014 #1
    1. The problem statement, all variables and given/known data
    Find Vx.
    http://imageshack.com/a/img853/3093/ssdr.png [Broken]

    2. Relevant equations
    NONE


    3. The attempt at a solution
    I just need one more equation so far I have:
    1. V1 = 4v
    2. V3 = 2Vx
    3. (V1-V2)/2 = V2-V3+V2
     
    Last edited by a moderator: May 6, 2017
  2. jcsd
  3. Feb 1, 2014 #2

    You made a error

    (V1 - V2)/2Ω = V2/1Ω + ??
     
    Last edited: Feb 1, 2014
  4. Feb 1, 2014 #3
    I don't see the error. The voltage is dropping across the resistor from V2 to V3. Likewise for the other one ohm resistor from V2 to ground.
     
  5. Feb 1, 2014 #4

    How can this be true if the left side of a the equation has a unit of Amps.
    (V - V)/Ω = V/Ω = A
    But on the right side you only have a voltage.
    And as we all know Ampere are not equal to Volts
     
  6. Feb 1, 2014 #5

    Nugso

    User Avatar
    Gold Member

    Well I guess the equation he meant to write is:

    (V1-V2)/2 = (V2-V3)/1 + (V2-0)/1 which is equal to (V1-V2)/2 = V2-V3 + V2
     
  7. Feb 1, 2014 #6
    Yeah sorry about the poor labeling, but Nugso is correct. I still can't figure out a third equation to get.
     
  8. Feb 1, 2014 #7
    Ok I see the problem.
    So all you need is this

    (V1-V2)/2 = (V2-V3)/1 + (V2-0)/1 (1)

    2Vx = V3 = 2(V1 - V2) (2)

    And you solve for V2.
     
  9. Feb 1, 2014 #8
    THANKS. Can't believe i didnt see that.
     
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