Use the node-voltage method to find how much power the current source extracts from the circuit if i=7.8 A and v = 35 V. Answer in watts.?

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  • 1 month ago

    Parallel combo of r's is 4.545ohms

    I(v)=-6.455A.  V(50)=67.273v

    P(i)=67.273v*7.8A=524.7W

    Circuit simulator applet 

  • 1 month ago

    This ckt only has one "Node" above the 50Ω since the 1Ω and 4Ω are in series.

    Let the bottom left of the ckt = ground and above the 50Ω be node V1

    KCL at V1:

    -7.8 + V1/50 + (V1-35)/5 = 0    Multiply eq. by 50

    -390 + V1 + 10V1 - 350 = 0

    11V1 = 350+390 = 740  so V1 = 750/11

    The current source delivers 740/11 * 7.8 = 5772/11 W = 524.73W

    The voltage source consumes 35V * 355/55 A = 225.91W

    The resistance consumes (74/55)²*50+(355/55)²*5 = 298.82W

    Total consumed = 225.91+298.82 = 524.73W  Checks

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