Finding Voltages Using KVL & KCL

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SUMMARY

This discussion focuses on applying Kirchhoff's Voltage Law (KVL) and Kirchhoff's Current Law (KCL) to solve a circuit analysis problem from a Physics 2 course. The user is attempting to determine the current directions and voltages in a circuit involving resistors R_1, R_2, and R_3, with specific currents i_0, i_1, i_2, and i_3. The user is uncertain about the direction of current i_3 and how to label the currents accurately, but is advised to assume a direction and proceed with the calculations, as incorrect assumptions will yield negative results.

PREREQUISITES
  • Understanding of Kirchhoff's Voltage Law (KVL)
  • Understanding of Kirchhoff's Current Law (KCL)
  • Basic circuit analysis techniques
  • Familiarity with resistors and current flow in electrical circuits
NEXT STEPS
  • Study the application of KVL in complex circuits
  • Learn about mesh analysis for circuit solving
  • Explore the concept of current division in parallel circuits
  • Review examples of circuit problems involving multiple loops and nodes
USEFUL FOR

Students in introductory physics or electrical engineering courses, particularly those learning circuit analysis techniques involving KVL and KCL.

nothingsus
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Homework Statement


http://imgur.com/a/L82gU
CH27P035.png

[Mod note: Inserted image inline for convenience]

Homework Equations


KVL, KCL

The Attempt at a Solution


[/B]
one of my equations will be at one of the nodes and will include all 3 currents.

i can also draw two loops, one for the upper triangle and one for the bottom triangle, however the signs of the terms will depend on the directions of the current, and I don't know which way i_3 will go!So this is a question from my Physics 2 course.

I've googled online for similar problems however most of them use more advanced techniques like mesh currents which I don't think is expected in my course.

We've only learned
1. algebraic sum of voltages about a closed loop is zero
2. current in = current out at a node

So I'm trying to label which way the current splits and the directions so I can write equations with the two above facts in mind, but I'm not really sure.

current is i_0 between the positive terminal of the battery and node A.

At node A, i_0 splits into i_1 (for the branch with R_1) and i_2 (for the branch with R_2).

i_1 should be greater than i_2 since current takes the path of least resistance.

When i_1 and i_2 reach nodes B and C respectively, I'm not really sure what happens. I don't know what direction (left or right) the current i_3 (flowing through R_3) should be.

Also, since the bottom two resistors are also R_1 and R_2 (although R_1 is now on the left and R_2 is now on the right) would they have the same currents i_1 and i_2 through them? What if they were some other resistances?
 

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nothingsus said:
I don't know which way i_3 will go
You don't need to predict it correctly. Just assume one way and write all the equations accordingly. If you guessed wrongly you will get a negative answer.
 

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