Circuit Analysis Question -- 2 sources and 4 resistors

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SUMMARY

The discussion revolves around solving a circuit analysis problem using the power supplied equals power absorbed method, rather than Kirchhoff's Voltage Rule. The user initially calculated the power supplied as 180 + 15x and the power absorbed as 72 + 56 + 28 + 3x, leading to an incorrect value for x. After clarification, it was established that two separate variables, I0 and V0, should be used, with I0 known to be 3A. The final resolution confirmed that the user correctly identified the dependent source voltage as 5I0.

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jisbon
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Homework Statement
As shown below.
Relevant Equations
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1586331720640.png

Now, I know this question can be solved using Kirchoff Voltage rule, but the question expliciitly wants me to use power supplied = power absorbed. Hence taking V0 to be x, I can't still seem to calculate. Any ideas?

Power supplied = (60)(3) + (5x)(3) = 180+15x
Power absorbed = 72+ 56 +28 + 3x

``180+15x = 72+ 56 +28 + 3x
x =2 which is obviously wrong. Any ideas?
 
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The dependent source voltage is 5IO. IO is known.
 
Last edited:
Is there something wrong with this exercise ? I see 30 V on the left and then 12 V over the top left resisitance.
So the 1`8 V is a giveaway !

I suppose that is what the OP means with
jisbon said:
I know this question can be solved using Kirchoff Voltage rule
But why come up with a 'hint' (that is perceived as force) that needs a lot of calculation ?
 
Good point, BvU. I too, had fallen victim to the Jedi mind-trick.
 
jisbon said:
Power supplied = (60)(3) + (5x)(3) = 180+15x
Power absorbed = 72+ 56 +28 + 3x

``180+15x = 72+ 56 +28 + 3x
x =2 which is obviously wrong. Any ideas?
You used x for I0 in the top equation and x for V0 in the bottom equation.
 
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phyzguy said:
You used x for I0 in the top equation and x for V0 in the bottom equation.
Hmm seems like you are correct. But with now having two separate variables, how do I solve them now?
``180+15y = 72+ 56 +28 + 3x where y is I0 and x is V0
 
lewando said:
The dependent source voltage is 5IO. IO is known.
I0 is 3A right? So wouldn't the power be (5*3)A *V0?
 
IO is 2A as indicated (at the top of the circuit). Why do you think VO has anything to do with the power supplied by the dependent voltage source?
 
lewando said:
IO is 2A as indicated (at the top of the circuit). Why do you think VO has anything to do with the power supplied by the dependent voltage source?
Sorry for being careless wow :/ Got the answer too, thanks
 

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