Solving Kirchoff's Loop Rule: Is My Equation Correct?

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Homework Help Overview

The discussion revolves around applying Kirchhoff's Loop Rule to a circuit analysis problem. The original poster is questioning the correctness of their equations related to current and voltage in a loop, particularly focusing on the signs used in their equations.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants are discussing the validity of the equations presented by the original poster, particularly the signs in the equations. There are questions about the direction of current and voltage drops across resistors, as well as the implications of the equations on the expected current values.

Discussion Status

There is an active exploration of the equations with participants providing feedback on the signs and suggesting amendments. Some participants are questioning the assumptions made about current directions and the resulting values, indicating a productive dialogue without a clear consensus.

Contextual Notes

Participants are working with a specific circuit diagram referenced by the original poster, which is not visible in the thread. There are indications of confusion regarding the signs in the equations and the expected outcomes based on Kirchhoff's laws.

willydavidjr
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I have a diagram on my website and I also attached it to this message. My question is I am wondering if my equation for this loop rule is correct. I am trying to solve it but I am having a problem about the signs I am getting..

This is my equation for this loop:


[tex]I_2=I_1+I_3[/tex]

[tex]6V-2I_3-2I_2=0[/tex]

[tex]1V-2I_3-I_1=0[/tex]

Do you think the above equations are correct?I used the equations but I get different signs that doesn't match the circuit on the diagram...

This is the site of the circuit: www.geocities.com/willydavidjr/loop.html
 

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Last equation is +I1. Look at the voltage *increase* through R1 in that direction due to I1.
 
I see. Do you think berkeman the second equation should be 6V - 2I3 + 2I2=0? What do you think?
 
I don't think that the third equation should be +I1. Because we will get negative answer for I3 and I1. Meaning they have opposite direction and it shouldn't be!
 
willydavidjr said:
I see. Do you think berkeman the second equation should be 6V - 2I3 + 2I2=0? What do you think?

The second equation is fine as you wrote it (why do you think the sign is wrong ?). Just amend the third equation as berkeman suggested.

When taking a loop across a resistance, if going with the labelled flow of current, use the minus sign. If going against the labelled flow of current, use the plus sign.
 
Berkeman what I get for this three equation just as I amended the 3rd equation are I1= 1 amp, I2= 1 amp and I3= 1 amp. Am I correct? I expected to get a negative value for I1 but I didn't get it. All have positive values. Do you think all flow of currents are correct?
 
How can they all equal 1A when your first equation says I2=I1+I3 ?

When you get the answers, just go back and put them on the original drawing, and see if all the voltages and currents add up.
 
No I mean 2A for I2. Sorry my fault.
 
willydavidjr said:
No I mean 2A for I2. Sorry my fault.

I replied to your PM. The answer is correct.
 

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