# Equivalent Resistance

1. Feb 15, 2010

### tmr0116

1. The problem statement, all variables and given/known data
Find the equivalent resistance between points a and b in the figure

2. Relevant equations
1/Req = 1/R1+1/R2... for parallel
Req= R1+R2... for series

3. The attempt at a solution
12.63 ohms

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2. Feb 15, 2010

### xcvxcvvc

3. Feb 15, 2010

### tmr0116

I have that the 4 and 2 ohm resistor are in series and add to be 6 ohms equivalent resistor. The 6 ohm resistor and the 3 ohm resistor are parallel and 1/6+1/3=1/2 or 2 ohms equivalent. I don't know what to do next though. Are the 1, 2, and 10 ohm resistors in series?

4. Feb 15, 2010

### vela

Staff Emeritus
No. If two elements are in series, all the current that goes through one has to go through the other. A current flowing through the 10-ohm resistor can go through the 9-ohm resistor or the 2-ohm resistor, so the 10-ohm resistor and the 2-ohm resistor are not in series. In contrast, all of the current in the 2-ohm resistor must also go through the 1-ohm resistor, so those resistors are in series.

5. Feb 16, 2010

### zgozvrm

Try re-drawing the circuit with your new values ... it may become clearer that way. Sometimes, it helps to re-draw the circuit vertically: in your case with "a" at the top of the diagram and "b" at the bottom.