# Circuit analysis equations

1. Dec 9, 2012

### brittydagal

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

Alrighty, my question is the exact same one that is written in this post - https://www.physicsforums.com/showthread.php?t=528337

The issue I'm having is understanding how to make/write my equations. I guess I just don't understand how you can know which way the current goes when you hit an intersection. I would LOVE it if someone could go through how they decided what the equations equal. I understand that you start at the battery (or at least I like to) and I usually move from - to + on the battery and then try to track the current but I get confused!! I would show you my photo of the current but I changed it a million times so it looks pretty weird.

Anyways- Can anyone give me the super detailed, step by step?

Thanks- Studying for exams :P

2. Relevant equations

P = IV
V = IR

Last edited by a moderator: Dec 9, 2012
2. Dec 10, 2012

### CWatters

As long as you are consistent with your notation it shouldn't matter which way you assume the current will go. If you define one way as +ve and your assumption turns out to be wrong the value you calculate will be -ve.

Try defining the currents so that you can write I1 + I2 + I3 = 0 rather than trying to guess the direction and writing I1 + I2 = I3

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