Kirchhoff's Law circuit question

In summary, the conversation is about finding the current flowing through each resistor in a circuit. The person has uploaded their attempt but is struggling to understand Kirchhoff's laws. They ask for help and someone suggests marking the potentials on the circuit to determine the direction of current flow. The person apologizes for uploading the circuit layout vertically and rotates it for easier viewing. They then have a second attempt at solving the problem and arrive at different answers. Finally, they figure out their mistake and confirm the correct answers with the other person.
  • #1
RyanTG
13
0
I've attached the circuit layout.

Q) Find the current flowing through each of the resistors.

I've uploaded my attempt.


What am I doing wrong? I thoroughly do not understand kirchhoff laws. I follow the sign rules, I try to do the maxwell loop thing and I'm still getting wrong answers.

If I do the maxwell loop on the circuit, is there no need for a I0? If I don't do the maxwell loop then I never get the right answer for any of the questions.

I don't understand why I can't do this.

Thanks.
 

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  • #2
You're asking for help and you post the work SIDEWAYS? Doesn't work for me. No interest in getting a kink in my neck.
 
  • #3
Maybe it could stem from the fact that you have current flowing both to the top of the page and to the bottom of the page, at the same time, through the middle section with the 4 ohm wire... Mark your potentials on the circuit to see which way the current's flowing.
 
  • #4
What's the potential at the junction above the 4 ohm resistor? What does that tell you about the potential difference across the 1ohm resistor? What does that tell you about the current through the 1 ohm resistor remember V = IR.
 
  • #5
I'm sorry man, it is saved vertically on my computer, I didn't purposefully upload it to be awkward.

There is no harm in just saving it to your computer and rotating it. I don't understand why I would be denied help because of something as petty as that.

Here you go, rotated.


Having a second go at it, I'm getting I1 as -4.5A, but a different value for I2 depending on which way I do my maxwell loop thing in the second half of the circuit...
 

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  • #6
Oh I think I get it now.

Is the correct answer: I1 = -5A, I2 = 5.5A?

Should the maxwell loop always go in the direction that the current would flow in that part of the circuit? So for the second half, it should go positive to negative, so my loop is the wrong way around?

And I've been plugging I1 back into the first simultaneous equation that governs the emf for the first loop, instead of plugging it into the second one, to find I2.
 
  • #7
You know what I don't even know anymore...
 
  • #8
figured it out finally i think... my answers were correct in that image, my method is wrong but just happened to be correct in that instance.
 
  • #9
I got those numbers as well, but i think you have to add them together through the 4 ohm resistor, so .5 through the 1 ohm and 1.5A through the 1 ohm.
 

1. What is Kirchhoff's Law?

Kirchhoff's Law, also known as Kirchhoff's Circuit Law, is a fundamental principle in circuit analysis that describes the conservation of charge and energy in an electrical circuit. It is used to determine the voltage and current at any point in a circuit.

2. What are the two laws of Kirchhoff's Law?

Kirchhoff's Law consists of two laws: Kirchhoff's Current Law (KCL) and Kirchhoff's Voltage Law (KVL). KCL states that the algebraic sum of currents entering and exiting a node in a circuit is equal to zero. KVL states that the sum of the voltage drops around a closed loop in a circuit is equal to the sum of the voltage sources in that loop.

3. How do you apply Kirchhoff's Law in a circuit?

To apply Kirchhoff's Law in a circuit, you must first draw a circuit diagram and label all the components and their respective values. Then, you can use KCL and KVL to write equations for the currents and voltages in the circuit. Finally, you can solve these equations to find the unknown values.

4. Can Kirchhoff's Law be applied to both series and parallel circuits?

Yes, Kirchhoff's Law can be applied to both series and parallel circuits. In series circuits, KVL is used to analyze the voltage drops across each component, while in parallel circuits, KCL is used to analyze the currents at each branch.

5. What are the limitations of Kirchhoff's Law?

Kirchhoff's Law assumes that the circuit components are ideal, meaning they have no resistance or capacitance. In real-world circuits, this is not the case, so there may be some discrepancies between the predicted and actual values. Additionally, Kirchhoff's Law does not take into account the effects of electromagnetic interference or non-linear components.

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