# Homework Help: Wrong final result in superposition theorem

1. Apr 3, 2012

### cel13

I have this assignment, basically I had to do the same thing in simplified way and then superposition theorem. Apparently the answers don't match. I'm pretty sure the mistake is in superposition theorem. It could be some really stupid and simple mistake I made since I'm no good at this at all.

I'd be really grateful if anyone could help me fix it.

I=U/R
I1=-2,2 I1=5/10
I2=0,4 I2=15/10
I3=-1,8 I3=30/10

K1=I1-I2+I3
K2=E1-E2=I1*R1*R2
K3=E2-E3=I2(R2+R3)
K2=5-15=I1*10+I2*15
I1=10+20+15I2=30+15I2
K22=15*30=I2=(-15)+I3*15
I2=15+30-15+15I3=153

16I2=15I1
I2=0,938I1

I1=30+15*0,938I1
I1=30+I10,7I1
-13,07I1=30
I1=-2,2

I2=0,938*(-2,2)
I2=0,4
I3=-2,2-(-0,4)
I=-1,8
R1kogu=R1+(R2*R3)/R2+R3
R1kogu=10+(15*15)/15+15=10+7,5=17,5
I1=E1/R1total=5/17,5=0,286
U1=R1*I1=17,5*0,286=5,005
I2=U2/R2
I2=0,005/15=0,0003
I3=0,0286-0,0003
I3=0,2867

RtotalR2=(R1*R3)/(R1+R3)=15+(10*15)/(10+15)=6+15=21
I2=15/21=0,714
U2=R2*I2=15*0,714=10,71
U1=U2=E2-U2=15-10,71=4,29
I3=4,29/15=0,286
I1=I2+I3=0,714+0,286
R3total=R3+(R1*R2)/(R1+R2)=15+(10*15)/(10*15)=21
I'''3=15/21=0,714

U3=R3*I'''3=15*0,714=10,71
U1=U3*E3-U3=15-10,71=4,29
I''2=4,29/15=0,286
I'''1=I2+I3=0,714+0,286=1 A

Current: 1A, I2 = 0,286 and I3 = 0,714

So this is it, any kind of help would be greatly appreciated. Thanks for your time.

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Last edited: Apr 3, 2012
2. Apr 3, 2012

### RoshanBBQ

It is hard to help without a picture of the circuit. Could you upload one?

3. Apr 3, 2012

### cel13

Oh sorry, I completely forgot it. I attached it now to the original post.

4. Apr 3, 2012

### NewtonianAlch

What's the question? What exactly are you looking for? Is that circuit diagram part of the original question? What is kogu?

It would also help not writing equations like this:

I1=10+20+15I2=30+15I2

The 15*I2 can be mistaken for 1512.

I don't mean to be rude, but most of that is not very easy to follow at all. If you did the actual question like that, it could be why you're getting an error somewhere.

5. Apr 3, 2012

### cel13

"Kogu" means total. The assignment isn't in english. I copied it directly from a word document, so the format got messed up a bit. I'll try to make it more readable.

Yes, this circuit diagram came with the assignment. I need help finding an error, the final result is incorrect.