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

## Homework Equations

I3 + I1= I2

- Thread starter chuvacjoe
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I3 + I1= I2

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TSny

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It is very important to specify the directions that you are assuming for each of the three currents. Otherwise, there is no way for us to check the signs in your equations.

For each equation you should state whether it comes from a junction rule or from a loop rule; and, tell us which junction/loop corresponds to each equation.

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Equation #2- Upper Loop clockwise from 20V source

Equations #3- Lower Loop rule counterclockwise

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TSny

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TSny

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TSny

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Note that the equation I

But, OK. We now have definite directions for the currents:

Your junction equation I

Let's look at your loop equation for the top loop. You wrote

20 - 30I

There is a sign error in this equation. Can you explain why you chose each of the four signs on the left?

Why +20? Why - 30I

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TSny

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So, for example, if you end up getting I

But it is essential to make an initial choice for the direction of each current and stick with that choice while setting up the signs in your equations.

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