Kirchoff's Rules: Solve P28.19 Circuit

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Homework Help Overview

The problem involves analyzing a circuit using Kirchhoff's Rules to determine the current in each branch. The context is rooted in circuit analysis, specifically focusing on current and voltage relationships within the circuit as described in Figure P28.19.

Discussion Character

  • Exploratory, Conceptual clarification, Problem interpretation

Approaches and Questions Raised

  • Participants discuss starting points for applying Kirchhoff's Current Law (KCL) and Kirchhoff's Voltage Law (KVL). There are suggestions to define unknown currents and write equations based on circuit nodes. Some participants express uncertainty about how to begin and seek clarification on the application of the laws.

Discussion Status

Participants are actively engaging in the problem, with some providing hints and guidance on how to approach the equations. There is a focus on defining variables and writing KCL equations, but no consensus has been reached on the next steps or specific methods to solve the problem.

Contextual Notes

Some participants note the importance of showing work to facilitate further assistance, and there is an emphasis on understanding the definitions and implications of KCL and KVL in the context of the circuit.

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Homework Statement


Determine the current in each branch of the circuit shown in Figure P28.19 (attached)


Homework Equations



Kirchoff's Rules:
[tex]\Sigma I_{in} = \Sigma I_{out}[/tex]
[tex]\Sigma \Delta V = 0[/tex]



The Attempt at a Solution



I have no idea where to begin. It's in the Kirchoff's rules section, so I'm assuming those will be used, but how I don't know how to apply them.
 

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Begin at the beginning. Explain what the KCL (1st equation) means, and what the KVL (2nd equation) means.

Then start with the KCL equations for the circuit. Call the bottom node ground, and write the 2 KCL equations for the two top nodes. There are three branches out of the top left node, and two branches out of the top right node... That gives you two equations and two unknowns (the top two node voltages are the unknowns)...

Show us some work, so that we can help you more. That's how it works here on the PF.
 
Oh, and you might try following the "Similar Threads" links at the bottom of the page, in case that helps to get you started writing the equations here in your own thread.
 
… give the unknowns names …

Hi clairez93! :smile:

Hint: start by calling the three unknown currents a b and c (with arrows).

Then write out all the Kirchoff's equations you can think of … what do you get? :smile:
 
Okay, so I have this a current I labeled a going upward along the vertical line at the far right with the 1 ohm resistor in it. Then b and c going downwards along the lines with the 8 ohm resistor and the 5 and 1 ohm resistor line. (b for the 5 & 1 ohm resistor line, and c for the one with 8)

I'm thinking a = b+c according to Kirchoff's first?
 
clairez93 said:
Okay, so I have this a current I labeled a going upward along the vertical line at the far right with the 1 ohm resistor in it. Then b and c going downwards along the lines with the 8 ohm resistor and the 5 and 1 ohm resistor line. (b for the 5 & 1 ohm resistor line, and c for the one with 8)

I'm thinking a = b+c according to Kirchoff's first?

Looks good! :smile:

Now what about the voltage drops across the resistors?

(going to bed now … :zzz:)
 

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