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Nodal Analysis question please help me

  1. Feb 15, 2013 #1
    1. The problem statement, all variables and given/known data

    Using Nodal analysis, determine the current through each resistor, for this circuit. Could you please show the KCL working out.I need the answers Please help me i am helpless with nodal analysis consist of a current source.Thanks in advance :) !!!!!.please help me.

    r1=120
    r2=360
    r3=330
    r4=820
    r5=100
    r6=470
    i1=15mA
    2. Relevant equations
    i1 + i2 + i3 = 0 ?

    3) The attempt at a solution
    first i converted the current sources and apply kcl for node 1.
    For node1:
    (9-v1)/120+(-4.95-v1)/560=0
    so v1=7.41176v
    For node 2:
    v2/820+(5--v2)/570=0
    so v2=3v.

    I assumed that all currents are comming in.

    nodal.jpg


    I really want the answers please :cry::cry:[/quote]

    .
    Please click on the image to zoom
     
    Last edited by a moderator: Feb 15, 2013
  2. jcsd
  3. Feb 15, 2013 #2

    gneill

    User Avatar

    Staff: Mentor

    You'll have to show an attempt so that we can know how to help; we won't do your homework for you here.

    Presumably the list of resistances you've given are for the first circuit, but you've listed seven resistors when the circuit shows only six :confused: Also, it's difficult to make out the values on the voltage supplies from the image; you'll have to clarify them.

    Start by identifying your reference node and labeling the others. Then make an attempt at writing node equations so we can see your level of understanding. If you have absolutely no idea what any of this means, you'll have to review your text and notes first.
     
    Last edited by a moderator: Feb 15, 2013
  4. Feb 15, 2013 #3

    first i converted the current sources and apply kcl for node 1.
    For node1:
    (9-v1)/120+(-4.95-v1)/560=0
    so v1=7.41176v
    For node 2:
    v2/820+(5--v2)/570=0
    so v2=3v.
     
  5. Feb 15, 2013 #4

    gneill

    User Avatar

    Staff: Mentor

    It's not necessary to convert the current source; You're writing KCL equations for nodes, and the given current source just needs to be added to or subtracted from the current totals for the nodes it connects to. But it's okay to convert wish, it's just a bit of extra work for you. You should make clear what the converted source is. What's its potential, resistance, and orientation?

    You haven't specified which nodes are which, so it's difficult to tell what your equations represent. Where's the reference node? Which node is node 1? Which is node 2? What's the value of the E1 source (looks like it might be 9V from the equations you wrote).
     
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