# circuit analysis textbook

Discussion in 'Homework Help' started by yiannistamv, Jul 23, 2014.

1. ### yiannistamv Thread Starter Member

Jul 23, 2014
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help for a topic in Fundamentals of Electric Circuits (5th Ed)

2. ### yiannistamv Thread Starter Member

Jul 23, 2014
35
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i am studing circuit analysis from the book Fundamentals of Electric Circuits (5th Ed) and i have stuck please can someone help?

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3. ### Jony130 AAC Fanatic!

Feb 17, 2009
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Equation 2.6.1 is correct.
Don't forget that in mesh analysis we can choose current direction arbitrary.
The author choose clockwise direction and by doing this he clearly defined polarities (the voltage drops) across resistors in the circuit according to the assumed directions of the mesh currents.

And this is why KVL looks like this

-12V + 4Ω*I + 2*Vo - 4V + 6Ω*I1 = 0

And Vo do not show the voltage polarities across 6Ω resistor.
This Vo show as how our VCVS will "sample/see" the voltage across 6Ω resistor.
And for our assumed current direction VCVS will "sample" negative voltage.
And this is why Vo = -6Ω*I

And for example if we assume counterclockwise direction we have this situation

And KVL

4V - 2*Vo + 4Ω*I + 12V + 6Ω I = 0

And

Vo = 6Ω*I

And finally we can use third method.

-12V + 4Ω*I + 2*Vo - 4V - Vo = 0

And Vo = -6Ω*I is negative because the Vo polarity is opposite to the direction of the loop current.

So

-12V + 4Ω*I + 2*(-6Ω*I ) - 4V - (-6Ω*I ) = 0

-12V + 4Ω*I + 2*(-6Ω*I ) - 4V + 6Ω*I ) = 0

-12V + 4Ω*I - 2*(6Ω*I ) - 4V + 6Ω*I = 0

-16 - 2*I = 0

and so on

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4. ### yiannistamv Thread Starter Member

Jul 23, 2014
35
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thank you very much Jony130
bust what vcvs means? thank you for your time

5. ### yiannistamv Thread Starter Member

Jul 23, 2014
35
0
Jony130 you are a life saver i find what vcvs MEANS i do understand thank you

Last edited: Jul 23, 2014