Kirchoff's Voltage Law transposing problem

Click For Summary

Homework Help Overview

The discussion revolves around applying Kirchhoff's Voltage Law (KVL) and Kirchhoff's Current Law (KCL) to a circuit problem involving multiple currents (I1, I2, I3) and voltages (V1, V2, V3). Participants are attempting to clarify the correct setup of equations based on their understanding of these laws.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants are discussing the formulation of equations based on KVL and KCL, questioning the correctness of their initial assumptions about current directions and the relationships between the currents. There is a focus on ensuring that the equations reflect the physical laws accurately.

Discussion Status

Some participants have offered guidance on the need for three independent equations due to the three variables involved. There is an ongoing exploration of how to correctly apply KVL and KCL to derive these equations, with some participants expressing uncertainty about their previous setups.

Contextual Notes

Participants are navigating potential confusion regarding current directions and their impact on the equations. There is mention of differing notes and interpretations, which may affect the formulation of the circuit equations.

JKhim
Messages
8
Reaction score
0
Homework Statement
So guys, its good to be back here and ask some of your opinions. Im new in this community, so i hope you'll guide me for a good start. Thank you

So here is my problem about Kirchoff's Voltage Law
When I substitute all the givens in the equation, i got confused because the notes i got from my classmate and my source in the internet is different on how it tranposed.

So guys, I will send a picture of the circuit given problem, and the solution i got using the notes of my classmate that he got in our physics teacher because that time, i was absent for certain reasons, and also the solution i got using the information in internet, it has many comments and reactions so i looked up to it and use it as a guide or basis too.

Feel free to ask about my work guys
Relevant Equations
V1-I1R1-I2R2-V2=0
241082

241083
241084
 
Physics news on Phys.org
To be clarify:
The calculation i got first is this:
V1-I1R1-I2R2-V2=0
5I1+10I2=6V+6V
5I1+10I2=12V
0.42I1+0.83I2=1
Second:
V1-I1R1-I2R2-V2=0
6V-5I1-10I2-6V=0
5I1+10I2=0
Which is correct guys? i feel sorry to myself because i got this trust issue in my doings, and I am just asking about your opinions because i know you can help me to clarify things, because this little confusion can affect all my other answers, and it might lose points in my assignment. I hope you will help me
 
Your I1, I2 and I3 are all flowing away from the middle junction. As per KCL, their sum should be zero.
 
cnh1995 said:
Your I1, I2 and I3 are all flowing away from the middle junction. As per KCL, their sum should be zero.
So you're saying that my kcl is wrong, instead of I2=I1+I3, it should I1+I2+I3=0 and by transposing it we get -(I1+I3) = I2, is that correct?
 
Last edited:
You need 3 independent equations here as you have three variables I1, I2 and I3.
JKhim said:
So you're saying that my kcl is wrong, instead of I2=I1+I3, it should I1+I2+I3=0 and by transposing it we get -(I1+I3) = I2, is that correct?
Yes.
That is one of the 3 equations.

Can you find the other two?
Use KVL in the two loops.
 
I think i got the right kvl when you say that all the currents in the problem are moving away, because i always think that these directions are just a design and not to include in a certain circuit problem, i used to follow the notes of mine even if it has a different directions, so i think this is the right equation to be used since it has the opposite direction i have in my notes.
Loop 1
V1+I1R1-I2R2-V2 = 0
Loop 2
V3+I3R3-I2R2-V2 = 0
 
Is my doings correct sir?
 
JKhim said:
V1+I1R1-I2R2-V2 = 0
Loop 2
V3+I3R3-I2R2-V2 = 0
Yes, now you can solve the three equations to get the three currents.
 

Similar threads

Replies
4
Views
1K
  • · Replies 9 ·
Replies
9
Views
4K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 13 ·
Replies
13
Views
1K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 7 ·
Replies
7
Views
1K
  • · Replies 2 ·
Replies
2
Views
5K