# Kirchoff's loop rule

1. Sep 11, 2013

### Sastronaut

1. The problem statement, all variables and given/known data

Compute the current through R2 of the circuit in the figure.

2. Relevant equations
kirchoff's loop rule
V=IR

3. The attempt at a solution
Junction: I1+I2=I3

Alpha loop: V1-I3R3-I5R5=0
I1=(V1-I5R5)/R3=?

Beta loop: V2-I8R8-I5R5=0

*without one of the currents provided I am not exactly sure where to proceed from here...any help would be greatly appreciated! Anything that is a different color than black in the figure is what I added to the circuit diagram! Thank You PF!

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2. Sep 11, 2013

### Pythagorean

You have two of the currents (in terms of other variables) so you can find the third.

3. Sep 11, 2013

### Sastronaut

I have been trying to figure out the algebra but I am always left with two variable (grouping of I1, I2, or I3). I am not sure how I can get it down to just one variable for current...

4. Sep 11, 2013

### Pythagorean

start here:

I3 = I1 + I2

and you know what I1 and I2 are, yeah? So....

I3 = ?

5. Sep 11, 2013

### Sastronaut

I3=(-5v+(5ΩI8))/-8Ω

?????

6. Sep 11, 2013

### Pythagorean

I'm not sure what you did there... I1 and I2 will be in terms of I3 and your knowns.

Actually, I'm not quite sure what you did for your alpha/beta loops either. There is no I5 or R5 or I8/R8. Don't try to plug in your values yet, just use the names of the constants.

7. Sep 11, 2013

### Sastronaut

I think I figured it out I have a value of 1.076A through R2. really appreciate the help :)