# Homework Help: Simplifying circuit diagrams

1. Mar 24, 2005

### F|234K

i want to transform the black diagram into a series and parellel circuit (as u a see that the black diagram isn't exactly series or parellel). i made the two top left resistors into one (blue circle), and i want to do the same thing for the other two in green circle. however, if i make the top right resistors in to one just like the top left ones, i won't get the right answer need for the problem. therefor, can someone please show me to right way to simplify this diagram?

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2. Mar 24, 2005

### whozum

I cant see the diagram but

For series: $$R_{eq} = R_1 + R_2 + ... + R_n$$

For parallel: $$\frac{1}{R_{eq}} = \frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3} + ... + \frac{1}{R_n}$$

Last edited: Mar 24, 2005
3. Mar 24, 2005

### F|234K

why can't you see it? i can see it no problem....hmmm...

i know those equations.....anways..you' ll have to see my diagram to see what i am asking.

4. Mar 24, 2005

### whozum

It says its pending approval.

5. Mar 24, 2005

### F|234K

oh....(it's my first time posting pics)

6. Mar 24, 2005

### whozum

Why dont you go ahead and post the problem.

7. Mar 24, 2005

### F|234K

8. Mar 24, 2005

### whozum

What are the resistances of each one?
What are you trying to find?

9. Mar 24, 2005

### F|234K

well, that isn't really my problem, but if you want to know, R=2.2 (for every one).
i am trying to find the net resistance.

10. Mar 24, 2005

### whozum

Equivalent resistance in the blue circle is 4.4ohms. You cant reduce the two in the green circle alone because they are in parallel with the one just above the green circle. Ithink the equivalent resistance would be 0.733ohms for all 3.

edit: If you do the blue resistor with the one between the two, you should be able to simplify that section. The resistance would be 1/(1/4.4+1/2.2) = 1.466ohms.

Your circuit is now a 1.466 ohm resistor in parallel with (two 2.2 resistors in series), in series with a 2.2 ohm resistor.

Last edited: Mar 24, 2005
11. Mar 24, 2005

### F|234K

if the answer is 1/.733....then it's right...

12. Mar 24, 2005

### F|234K

why you can't combine the ones in the green circle?

13. Mar 24, 2005

### whozum

Because you have to keep in consideration Kirschoff's Law. The net current into a node is the net current out of a node. The net current coming out of the node on the bottom right of the green circle doesnt have all of the incoming current accounted for.

14. Mar 24, 2005

### F|234K

k, thanks a lot whozum.

15. Mar 24, 2005

### whozum

No problem. I got a equivalent resistance for the whole circuit of 2.57ohms. What were you trying to find the resistance of initially?

16. Mar 24, 2005

### F|234K

actually, the answer is 3.6 ohms.....

17. Mar 24, 2005

### whozum

Now im getting 3.52..

18. Mar 24, 2005

### F|234K

lol....the exact answer in the book is 3.575....

and i still can't get the answer...don't know what i am missing....

19. Mar 24, 2005

### whozum

Im drawing it all out. Hold on.

Last edited: Mar 24, 2005
20. Mar 24, 2005

### whozum

http://www.public.asu.edu/~hyousif/circuitreduction.JPG [Broken]

Last edited by a moderator: May 2, 2017