# Homework Help: Thevenin Circuit help

1. Jan 27, 2012

pic aint working, gonna upload it again. If you just copy & paste the URL it works fine
http://cottage7.angelfire.com/Thevenin.png

I've been using this site for a while but I finally have a problem that I could not relate to another on this site so here I am!

1. The problem statement, all variables and given/known data
I must calculate the current through R1 given:
R1=3Ω
R2=6Ω
R3=3Ω
R4=4Ω
R5=6Ω

R1 MUST be taken out and thevenin's theorem used.

2. Relevant equations
http://cottage7.angelfire.com/Thevenin.png
3. The attempt at a solution
i can't seem to wrap my head around on how to set up the loops. Pulling R1 (which is at a->b) leaves an ugly looking circuit.

Rth =(R2)(R3)/(R2+R3) + R4 + R5

is this thevenin resistance correct? Somebody told me to ignore R5 but that doesn't seem right.

Once i find Vth & Rth I imagine the rest will be simple, kirchhoff's rules & linear equations, etc.

#### Attached Files:

• ###### Thevenin.png
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Last edited by a moderator: Jan 27, 2012
2. Jan 27, 2012

### vela

Staff Emeritus
If you go to advanced mode, you can attach pictures so you don't have to host them somewhere else. I attached your diagram to the post for you.

3. Jan 27, 2012

### vela

Staff Emeritus
Your Thevenin resistance isn't correct. You want to replace the voltage sources by shorts.

As far as calculating the Thevenin voltage goes, you have only two loops. What current flows through R5 since it's not part of a loop?

Last edited: Jan 27, 2012