# Find Thevenin equivalent circuit

1. Feb 9, 2013

### leroyjenkens

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

Find Thevenin equivalent circuit as seen across terminals A and B for each circuit.

2. Relevant equations

$$V=IR$$

3. The attempt at a solution

Those resistors are in parallel because not all of the current going through the top one is going to go through the next one, right?
So I add the resistors to make an equivalent resistance, but I'm not sure what to do after that.

I need to find the open-circuit voltage, but I don't know how to do that mathematically.

And I need to find the short circuit current, which is $$I=\frac{V_T}{R_T}$$.

Is the $$V_T$$ just the voltage source? And is the $$R_T$$ just the equivalent resistance that I found?

Thanks.

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2. Feb 9, 2013

### rude man

See above.

3. Feb 10, 2013

### leroyjenkens

What do you mean by wrong argument? That's not the reason they're in parallel? There's a different reason they're in parallel? Or are they not in parallel at all?

The open circuit voltage would be $$V_{Th}=\frac{(2)(100)}{100+100}=1$$ right?

And the short circuit current would just ignore the middle resistor and that would be $$I=\frac{2}{100}=0.04A$$ right?

Ok so $$R_{Th}=\frac{1}{0.04}=25$$

So to answer the question posed, I would make a circuit replacing the $$V_{in}$$ with $$1V$$ and replace the two resistors with a 25 Ohm resistor?

Thanks for the response.

Last edited: Feb 10, 2013
4. Feb 10, 2013

See above.