Kirchhoff's Laws: Homework Solutions Check

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Homework Help Overview

The discussion revolves around applying Kirchhoff's Laws to a circuit problem, specifically focusing on current and voltage equations. Participants are examining the correctness of their equations and the signs of the currents involved.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants are questioning the signs of the currents in their equations and whether there are mistakes in their calculations. There is also a discussion about the necessity of the positive signs accompanying current arrows in the circuit diagram.

Discussion Status

The discussion is ongoing, with participants sharing their thoughts on the correctness of their signs and the clarity of their diagrams. Some guidance has been offered regarding the interpretation of current directions, but no consensus has been reached on the correctness of the equations.

Contextual Notes

There is a focus on the potential confusion arising from the signs of the currents and the representation of current directions in the diagram. Participants are also reflecting on the implications of their choices in labeling currents.

frazdaz
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Homework Statement



2s1n338.png


Homework Equations



[tex]\sum I_{in} = \sum I_{out}[/tex]
[tex]\sum \epsilon = \sum pd[/tex]

The Attempt at a Solution



Can anyone identify any mistakes in these? Probably signs

[tex]I = I_1 + I_2[/tex]
[tex]12=4I_1 +3I[/tex]
[tex]5=4I_1 - 2I_2[/tex]
[tex]12-5=2I_2+3I[/tex]
 
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What let's you think there are any mistakes ?
 
BvU said:
What let's you think there are any mistakes ?
The answers have I1 and I2 with opposite signs. I get them both as positive.
 
I make all currents positive for the directions shown.

I'm not sure what is achieved by that + sign accompanying each current arrow? It seems superfluous if it duplicates the function of the arrowhead, and just clutters the diagram.
 
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NascentOxygen said:
I make all currents positive for the directions shown.

I'm not sure what is achieved by that + sign accompanying each current arrow? It seems superfluous if it duplicates the function of the arrowhead, and just clutters the diagram.
Well that's good news. And, yeah, I guess it's just intended to help with the maths side of things.
 

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