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Homework Help: Fundamentals of Electrical Engineering Circuit Basics Question

  1. Jan 19, 2012 #1
    "Fundamentals of Electrical Engineering" Circuit Basics Question

    1. The problem statement, all variables and given/known data
    07ELr.jpg
    I am asked to find p1, p2, p3, p4.

    2. Relevant equations
    p=vi
    ƩP=0

    3. The attempt at a solution
    p1=(5)(-9)
    =-45
    p2=(2)(9)
    =18
    p4=(3)(5)
    =15

    p3=v(.6i)
    =v(.6(4))
    =v(2.4)
    I know that v=5 and p3=12, but I don't know why v=5.

    I do perfectly fine finding p1, p2, and p4, but I am having difficulty figuring out how to find the voltage on p3 to get the power. I am trying to refrain from using the law of the conservation of energy (ƩP=0), since a previous example I tried to figure out before gave me the same problem.
     
  2. jcsd
  3. Jan 19, 2012 #2

    gneill

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    Staff: Mentor

    Re: "Fundamentals of Electrical Engineering" Circuit Basics Question

    The diagram shows I = 5A. So the voltage on the controlled source should be 5*0.6 = 3V.
     
  4. Jan 19, 2012 #3
    Re: "Fundamentals of Electrical Engineering" Circuit Basics Question

    I am talking about the dependent voltage source, p3. The current is labeled as 4A.
     
  5. Jan 19, 2012 #4

    gneill

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    Staff: Mentor

    Re: "Fundamentals of Electrical Engineering" Circuit Basics Question

    Yes, the current through the controlled source is labelled as 4A. But the controlled source voltage is stated to be 0.6I, and I = 5A.
     
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