# Homework Help: Fundamentals of Electrical Engineering Circuit Basics Question

1. Jan 19, 2012

### Varro

"Fundamentals of Electrical Engineering" Circuit Basics Question

1. The problem statement, all variables and given/known data

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. Jan 19, 2012

### 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.

3. Jan 19, 2012

### Varro

Re: "Fundamentals of Electrical Engineering" Circuit Basics Question

I am talking about the dependent voltage source, p3. The current is labeled as 4A.

4. Jan 19, 2012

### 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.