# Resistance in a combination circuit

1. Mar 12, 2013

### wahaj

1. The problem statement, all variables and given/known data
Find the resistance in resistor MN. Diagram is attached

2. Relevant equations

in series circuit
R = R1+R2+R2+.......Rn
in parallel circuit
$$\frac{1}{R} = \frac{1}{R_1}+\frac{1}{R_2}+\frac{1}{R_3}+.... \frac{1}{R_n}$$
3. The attempt at a solution
I have no idea on how to get started. I was able to find the resistance between points K and L but I can't seem to make sense of how to draw a diagram for this. I just need a hint to get me started

#### Attached Files:

• ###### Circuit.jpg
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2. Mar 13, 2013

### SammyS

Staff Emeritus
Do all the resistors have the same resistance?

3. Mar 13, 2013

### wahaj

no all the resistances are different. I actually just wanted a better understanding of how to solve this kind of problem rather than solve this specific problem. The resistance in MN is 211 and was determined experimentally. I have to do a series/parallel analysis on the circuit to find the resistance in MN and see if the 2 resistances match within error range

4. Mar 13, 2013

### Simon Bridge

Do you need the total resistance between nodes M and N?

Draw the M node at the top and the N node at the bottom - imagine you put a battery with the + terminal at M and the negative at N ans see where the current can go. There are three possible paths. See now?

5. Mar 13, 2013

### wahaj

ok I got it thanks

6. Mar 13, 2013

### haruspex

How to combine them depends on the two points you pick. You want the resistance between K and L, yes? clearly MO, OP, PN are in series, so combine those first. How do you think you should combine the net of that with MN? Then with KM and NL?

7. Mar 13, 2013

### wahaj

I actually figured it out. It turns out I had the diagram drawn a bit wrong. but I fixed it thanks to you help

8. Mar 13, 2013

### haruspex

How to combine them depends on the two points you pick. You want the resistance between K and L, yes? clearly MO, OP, PN are in series, so combine those first. How do you think you should combine the net of that with MN? Then with KM and NL?