# Struggling with Thevenin Equivalent Problem

I had asked this question before and thought I had found the help I needed, but unfortunately I found myself unable to solve the problem fully when I attempted it. The problem:

For the Thevenin resistance, I believe I'm on the right track but am not confident in my answer: R5+(R4 ||(R2+R3)), excluding R1 because I believe it will become irrelevant if I short the voltage source?

As for the Thevenin voltage, I wasn't sure how I was supposed to go about solving it. Any insight would be appreciated.

• For Thevenin voltage you need to find the voltage on R4. Pretty easy. As you said, R1 is out as it is parallel to the source. R5 is out as well, as there is no current in it. Sep 28, 2018 at 18:32
• Just look at the circuit and see where the current flows and where it does NOT flow. For example, no current can flow through $R_5$. It's got nowhere to go. So if you can work out the current in $R_4$, then you can figure out the voltage across it. And if you know the voltage across it and if there is zero current in $R_5$ (no voltage drop, therefore), then you have your answer.
– jonk
Sep 28, 2018 at 18:40
• Thank you for the inputs, I was able to see what I wasn't seeing before. Sep 28, 2018 at 19:03

• What? How is $R_1$ out? Finding $V_{OC}$ doesn't involve shorting $R_1$ out. -1 Sep 28, 2018 at 19:34
Your approach to solving for $$\R_{th}\$$ is correct.
The quick answer is to note that no current flows through $$\R_5\$$, which means there's no voltage drop across it. Thus, all you need to do is solve for the voltage across $$\R_4\$$ in the simple two-loop circuit that remains.