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Validity of interconnection in electric circuit

  1. Sep 21, 2016 #1
    1. The problem statement, all variables and given/known data
    79Cs3YG.png

    2. Relevant equations
    P=Vi

    3. The attempt at a solution
    For part a, it looks like the dependent current source (4i1) leads directly to i1, with nothing that could change it. This would mean the interconnection is invalid, right? I can't tell if this circuit is in series or in parallel (is it both?), but I know independent voltage sources can't be parallel, and independent current sources can't be in series. I don't know which one would apply here though.

    If the circuit is invalid, then I'm not sure how to find the total energy developed, but I guess it would be P=Vi at each node.
     

    Attached Files:

  2. jcsd
  3. Sep 22, 2016 #2

    NascentOxygen

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    Staff: Mentor

    There are 2 independent current sources, together pushing how much current downwards to the lower node?
     
  4. Sep 22, 2016 #3
    Ah, so they push 240mA towards the lower node, with 4i1 leaving the node. And that would make i1=60mA.

    So then lower node = 0 = 180mA+60mA-4i1 = 180mA+60mA-4(60mA), which means it;s valid?
     
  5. Sep 22, 2016 #4

    NascentOxygen

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    Staff: Mentor

    Next, address the voltage sources. Do they look okay here?
     
  6. Sep 22, 2016 #5
    At the top node, according to KVL, the net voltage should be 0=v1+v2. But here, the voltages are in the same direction, and are of different magnitudes so they don't cancel out. Does the dependent current source generate voltage as well? I thought it just changed the current.
     
  7. Sep 22, 2016 #6

    NascentOxygen

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    Staff: Mentor

    Current sources adjust their terminal voltage to whatever is needed in order to force their designated current through the circuit.
     
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