(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

[PLAIN]http://dl.dropbox.com/u/9699560/EE%20Problem.jpg [Broken]

(I added the text V1, V2, and Voc to the image).

I'm only trying to find Voc because I got the wrong answer. I got Isc correct.

2. Relevant equations

Basic node voltage analysis techniques.

3. The attempt at a solution

Let the bottom-most node be the ground (reference node).

[itex]\begin{array}{rcl}

\dfrac{v_1}{2} + \dfrac{v_1-v_2}{3} & = & 0 \\

\dfrac{v_2-v_1}{3} + \dfrac{v_2-v_{oc}}{5} & = & 10 \\

\dfrac{v_{oc}-v_2}{5} & = & \dfrac{v_x}{4} \\

v_1 & = & v_x

\end{array}[/itex]

These simplify to:

[itex]\begin{array}{rcl}

5v_1 - 2v_2 + 0v_{oc} & = & 0 \\

-5v_1 + 8v_2 - 3v_{oc} & = & 150 \\

5v_1 + 4v_2 - 4v_{oc} & = & 0

\end{array}[/itex]

in matrix form:

[itex]\left[\begin{array}{rrrr}

5 & -2 & 0 & 0 \\

-5 & 8 & -3 & 150 \\

5 & 4 & -4 & 0

\end{array}\right][/itex]

Solving, this gives:

[itex]\begin{array}{cc}

v_1 & = & 40\, V\\

v_2 & = & 100\, V\\

v_{oc} & = & 150\, V

\end{array}[/itex]

However, 150 V is not the correct answer for Voc. Does anyone know where I have made a mistake?

Thanks!

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# Finding Thevenin Equivalent circuit (Voc)

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