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Homework Help: CIRCUIT ANALYSIS: 3 resistrs, I src, V src, V.C.V.S. in series w/ resistor - Find V_A

  1. Jan 22, 2007 #1
    1. The problem statement, all variables and given/known data

    Use nodal analysis to find [itex]V_A[/itex] in the circuit below.

    http://img180.imageshack.us/img180/7004/chapter3problem236vy.jpg [Broken]

    2. Relevant equations

    KVL, KCL, v = i R, super-node?

    3. The attempt at a solution

    I made a few currents and showed the obvious KVL loop.

    http://img201.imageshack.us/img201/4716/chapter3problem23part22nf.jpg [Broken]

    [tex]V_1\,=\,V_A[/tex] <---- Right?



    [tex]I_3\,=\,\frac{V_1\,-\,V_2}{4\Omega}[/tex] <------Right?

    I know KCL for [itex]V_1[/itex]:



    I know KCL for [itex]V_3[/itex]:



    For KVL1:



    Now, putting those three EQs into a matrix and rref:


    This gives me [itex]V_1\,=\,V_A[/itex] equal to 22.34 V.

    Thanks for the help mjsd!
    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. Jan 22, 2007 #2


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    Homework Helper

    all your equations look sound to me..
  4. Jan 22, 2007 #3


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    oh..hang on.... 2nd line for KCL for V3 is wrong where is the 48 gone?
  5. Jan 22, 2007 #4
    Corrected, thanks much!
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