# Series-paralell cirquit with only resistors.

Discussion in 'Homework Help' started by marouk, Aug 12, 2014.

1. ### marouk Thread Starter New Member

Aug 12, 2014
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I'm having trouble figuring out wich resistors are in paralell and wich are in series, can anybody help me? It was on a test in my university electronics class.

I have tried redrawing the circuit, but i get wrong answers, my teachers are on vacation so i thought i would try here!

2. ### jpanhalt AAC Fanatic!

Jan 18, 2008
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Does this re-draw help?

John

3. ### marouk Thread Starter New Member

Aug 12, 2014
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Thanks John i think it does!

(100+220)//(600//400+220//400)

Total impedance aproximately 174,1Ω

Is that correct or did i mess it up?

4. ### Ramussons Active Member

May 3, 2013
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{(400 || 600) + (400 || 220)} || (100 + 220)

Ramesh

5. ### marouk Thread Starter New Member

Aug 12, 2014
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I think that is what i did...

Got Total impedance aproximately 174,1Ω

6. ### jpanhalt AAC Fanatic!

Jan 18, 2008
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174.1 Ω is what I got too.

Please let us know how you do on the rest of the questions.

John

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7. ### marouk Thread Starter New Member

Aug 12, 2014
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I'm having some trouble (my brain is in vacation mode)...

In a paralell circuit the voltage is the same, so on my first try i got 32V on V1,V2 and Va, but this is sereis paralell and i'm not sure what to do, i'm reading about current dividers and voltage diveders now... All tips are apreciated!

8. ### marouk Thread Starter New Member

Aug 12, 2014
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Can the voltage be more than 32V? I tried voltage diveder formula for V1, V1=(600/174.1)*32V and got 110.3V

????????
Steinar

9. ### jpanhalt AAC Fanatic!

Jan 18, 2008
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Not in that circuit.

174.1 is the total resistance seen by the battery. Calculate the total current. Then calculate how that current is proportioned between the two main parallel legs (redrawn below):

Now, you can calculate the voltages across the 400 and 600 Ω resistors using their paralleled resistance.

John

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10. ### marouk Thread Starter New Member

Aug 12, 2014
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Ok, you are much better than my textbook... ;-p

I got 20.1 V for V1, but is it then the same for Va?

Feel kind of stupid right now....

11. ### jpanhalt AAC Fanatic!

Jan 18, 2008
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Wouldn't Va referenced to ground be (32 - V1)? You can double check that with the current you calculated and the paralleled resistance of the 220 Ω and 400 Ω resistors.

John