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Homework Help: Independent current and voltage network analysis

  1. Jan 21, 2012 #1
    1. The problem statement, all variables and given/known data
    Theres two current sources and three voltages sources the problem wants to know the power supplied by each current source

    2. Relevant equations
    according to the book the problem can be solved using Kirchoffs current law and kirchoffs voltage law

    The answers according to the textbook the 2mA current source supplies 6mW and the 1 mA current source supplies -7mW

    3. The attempt at a solution
    I can only guess that they subtract the 5v by the 8v then multiply the result by the 2mA.
    Also subtract the 15v by the 8v and multiply the result by the 1mA source to get the -7mW answer.

    Attached Files:

  2. jcsd
  3. Jan 24, 2012 #2


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    This is correct, but can you explain why? (I'm not sure about the signs though. I think they should be -6 mW and +7 mW, but I could be wrong.)
  4. Jan 25, 2012 #3


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    Staff: Mentor

    The +8v source sets the voltage between the far left and far right nodes to be 8v, with the left node positive. No IF's or BUT's about it.
  5. Jan 26, 2012 #4
    Best way to approach such ckt problems is to assume a reference node and assign a zero potential to it.Next move across the branches and assign voltages to other nodes by appropriately adding or subtracting voltages keeping in mind you assign movin from lower potential to higher potential a PLUS sign. Then you would have got voltages at all nodes then evaluate power using V*I . Power is being supplied or is positive if current is flowin from higher potential to lower potential and dissipated if vice versa.

    Hope its clear now
    Last edited by a moderator: Jan 26, 2012
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