Question on Thevenin's Theorem

Discussion in 'Homework Help' started by mngeow, Nov 27, 2010.

1. mngeow Thread Starter New Member

Jan 28, 2010
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I have an exam coming up on circuit theory & analysis,there's this one question I can't seem to get right.

Vab=Vth=V(8-j15)=V(6+j10) this is what I used to get my Vth.

For Zth I used R(8-j15) // R(6+j10).

What am I doing wrong?

Last edited: Nov 27, 2010
2. thatoneguy AAC Fanatic!

Feb 19, 2009
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It appears you are assuming points A and B have the same voltage.

3. mngeow Thread Starter New Member

Jan 28, 2010
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What do you mean?

4. thatoneguy AAC Fanatic!

Feb 19, 2009
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Warning - it's after bar hours for me...

5. mngeow Thread Starter New Member

Jan 28, 2010
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Hmm,thats the only way I could think of to get Vab,since R(8-j15) // R(6+j10).
What should the correct Vab be then?

6. thatoneguy AAC Fanatic!

Feb 19, 2009
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You have 2 unknowns (A and B).

You know the source voltage across both series circuits that source both A and B.

Simultaneous equations or matrix solution is what I'm thinking.

7. mngeow Thread Starter New Member

Jan 28, 2010
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You can use simultaneous equations?!?!
So far I've only learnt mesh analysis and the usual ohms law/kirchhoffs law so I'll have to get the answer using either one of those.

8. thatoneguy AAC Fanatic!

Feb 19, 2009
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Solving the two equations is an algebraic step, not something that EE teaches, other than the required math courses for EE.

Apr 26, 2005
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