Circuit Analysis Question -- 2 sources and 4 resistors

[jisbon]

Homework Statement

As shown below.

Relevant Equations

-

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?

 

[lewando]

The dependent source voltage is 5I_O. I_O is known.

 

[BvU]

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

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 ?

 

[lewando]

Good point, BvU. I too, had fallen victim to the Jedi mind-trick.

 

[phyzguy]

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.

 

[jisbon]

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

 

[jisbon]

The dependent source voltage is 5I_O. I_O is known.

I0 is 3A right? So wouldn't the power be (5*3)A *V0?

 

[lewando]

I_O is 2A as indicated (at the top of the circuit). Why do you think V_O has anything to do with the power supplied by the dependent voltage source?

 

[jisbon]

I_O is 2A as indicated (at the top of the circuit). Why do you think V_O has anything to do with the power supplied by the dependent voltage source?

Sorry for being careless wow :/ Got the answer too, thanks