# Effective resistance between two points

1. Oct 8, 2009

### DarylMBCP

Hey guys, I'm having a little troublt with rearranging resistors in a circuit to identify which are parallel and which are in series so I can decide how they should be added; RTotal = R1 + R2 or RTotal = 1/R1 + 1/R2.

Taking that each of the three resistors in the circuit shown (diagram attached) has a resistance of 6 ohms, what is the effective resistance between X and Y? The answer key shows that the three are parallel and if that is so, I knw how to calculate the effective resistance to get 2 ohms.

However, I'm not sure how to identify if they are parallel or not from the diagram. Any help is greatly appreciated. Thanks.

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2. Oct 8, 2009

### Redbelly98

Staff Emeritus
One little rule to make that decision is this: series elements have the same current, while parallel elements have the same voltage difference.

3. Oct 10, 2009

### DarylMBCP

Ok, so from the diagram I can see that the three resistors have different current passing through them but have the same voltage difference so the MUST be parallel, right? Is this method standard for all examples? Thanks for the help.

4. Oct 10, 2009

### Redbelly98

Staff Emeritus
Yes, same voltage means they are in parallel. And I'm pretty sure this method does work for any resistor circuit.