Nodal Analysis - No Resistor

Discussion in 'Homework Help' started by p75213, Aug 26, 2011.

  1. p75213

    Thread Starter Member

    May 24, 2011
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    I am having problems with this circuit. The circuit has 3 nodes - v1,v2 and v3. Solve for the voltage across the 3 ohm resistor using nodal analysis. the 3 equations I get are as follows:
    1) (v1-v3)/6-2+(v1-v2)/4+v1/0=0
    2) (v2-v1)/4+v2/0+(v2-v3)/2=0
    3) (v3-v1)/6+2+(v3-v2)/2+v3/3=0
    This is obviously wrong. The 1st equation has v1/0 and the second equation has v2/0. How do I get rid of them?
    Can somebody help with this please?
     
  2. t_n_k

    AAC Fanatic!

    Mar 6, 2009
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    Just to clarify your schematic. Is the earth [0V] connected to both the bottom "rung" and the center of the first "rung"?
     
  3. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    Simply ignore V3
    Write the nodal equation only for V1 and V2
     
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  4. p75213

    Thread Starter Member

    May 24, 2011
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    yes it is.
     
  5. p75213

    Thread Starter Member

    May 24, 2011
    39
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    Yes it is.
     
  6. p75213

    Thread Starter Member

    May 24, 2011
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    Could you clarify please?
     
  7. p75213

    Thread Starter Member

    May 24, 2011
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    Is there no current through v3? Ignoring v3 I get:
    1) (v1-v2)/6-2+v1/0=0
    2) (v2-v1)/6+2+v2/3=0

    I still have a divide by 0 in 1). Can v1/0 be replaced by -v2/3?
     
  8. t_n_k

    AAC Fanatic!

    Mar 6, 2009
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    It would be useful for you to re-draw the schematic taking account of which elements are connected to the common [0V] rail. You'll find that apart from the common node there is only one other node.
     
  9. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    Ok so the diagram look like this

    [​IMG]

    And we only have one unknown node voltage V1.
     
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