Kirchoff's Voltage Law transposing problem

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SUMMARY

The discussion focuses on applying Kirchoff's Voltage Law (KVL) and Kirchoff's Current Law (KCL) to solve a circuit problem involving three currents (I1, I2, I3) and two voltage sources (V1, V2). The correct formulation of KCL is established as I1 + I2 + I3 = 0, which is essential for solving the circuit. The participants confirm that using KVL in two loops, represented by the equations V1 + I1R1 - I2R2 - V2 = 0 and V3 + I3R3 - I2R2 - V2 = 0, is necessary to derive the values of the currents accurately. The discussion emphasizes the importance of correctly identifying current directions and formulating independent equations for accurate circuit analysis.

PREREQUISITES
  • Understanding of Kirchoff's Voltage Law (KVL)
  • Understanding of Kirchoff's Current Law (KCL)
  • Basic circuit analysis techniques
  • Familiarity with solving systems of equations
NEXT STEPS
  • Study advanced circuit analysis techniques using KVL and KCL
  • Learn how to solve systems of linear equations in electrical circuits
  • Explore the application of mesh and nodal analysis in circuit design
  • Investigate the impact of current direction on circuit equations
USEFUL FOR

Electrical engineering students, circuit designers, and anyone involved in circuit analysis and problem-solving using Kirchoff's laws.

JKhim
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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
 
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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.
 

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