Kirchoff's Voltage Law transposing problem

In summary, the conversation discusses the use of Kirchhoff's Current Law (KCL) and Kirchhoff's Voltage Law (KVL) to solve a circuit problem. It is clarified that the sum of the three currents must be zero according to KCL, and three independent equations are needed to find the three variables. The correct equations using KVL are provided and it is confirmed that the student's understanding is correct.
  • #1
JKhim
8
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
 
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  • #2
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
 
  • #3
Your I1, I2 and I3 are all flowing away from the middle junction. As per KCL, their sum should be zero.
 
  • #4
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:
  • #5
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.
 
  • #6
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
 
  • #7
Is my doings correct sir?
 
  • #8
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.
 

Related to Kirchoff's Voltage Law transposing problem

1. What is Kirchoff's Voltage Law?

Kirchoff's Voltage Law, also known as KVL, is a fundamental law in electrical circuit analysis that states that the sum of all voltages around a closed loop in a circuit must equal zero.

2. What is a "transposing problem" in relation to Kirchoff's Voltage Law?

A transposing problem refers to the process of rearranging the terms in a KVL equation in order to solve for a specific voltage or current. This is often necessary when analyzing complex circuits with multiple loops and unknowns.

3. Why is Kirchoff's Voltage Law important in circuit analysis?

KVL is important because it allows us to determine the voltage drops and currents in a circuit without having to measure them directly. This is especially useful when dealing with circuits that are too complex to analyze using basic Ohm's Law.

4. What are the steps for solving a Kirchoff's Voltage Law transposing problem?

The steps for solving a KVL transposing problem are: (1) Identify the closed loop in the circuit, (2) Assign a direction for each voltage and current in the loop, (3) Write out the KVL equation using the polarities of the components, (4) Rearrange the terms in the equation to isolate the desired voltage or current, and (5) Solve for the unknown using basic algebra.

5. What are some common mistakes to avoid when solving a Kirchoff's Voltage Law transposing problem?

Some common mistakes to avoid when solving a KVL transposing problem include: (1) Not properly assigning the polarities of the components, (2) Forgetting to include all the voltage drops in the loop, (3) Making sign errors when rearranging the equation, and (4) Not double-checking the units of the final answer.

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