Circuit Analysis KCL question

In summary, the conversation discusses finding the values of i_0, i_1, and i_2 given V_g = 54V. The attempt at a solution involves analyzing the leftmost closed loop and using KCL to determine the current at a node. However, there is confusion about the current flow and the possibility of all currents being equal to zero. It is also noted that the 10Ω and 5Ω resistors are in parallel and that the current source is producing 9A.
  • #1
ElijahRockers
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Homework Statement



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if [itex]V_g = 54V[/itex]

find [itex]i_0, i_1, i_2[/itex]

The Attempt at a Solution



In the left most closed loop, Since the source voltage is 54, I assumed there must be a voltage drop across the 12Ω and 6Ω resistors equal to 54. This makes VΔ 18V.

Next I tried to KCL the node below it, but it immediately confused me. If the current around the closed loop is 3A (which is what I calculated by doing a KVL of that leftmost loop), then how can there be any more current flowing into that node? Shouldn't i0 be 0?

Then, even if it is, that means in the righthand part of the circuit, one node has three currents leaving it and none coming in, while another node will have three currents entering it and none leaving. The only way I can think of that happening is if all the currents are equal to zero, but surely this is not the answer...

Anyway, the only other work I could do was to note that the 10Ω and 5Ω are in parallel, so i2 = 2i1. Also, the current source is producing 9A, since the supplied current is supposed to be VΔ/2, but that doesn't seem to help my situation much.
 
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  • #2
Shouldn't i0 be 0?
Yep! There is nowhere for the current to return...

one node has three currents leaving it and none coming in
That's just a sign thing. Currents can be negative.

i2 = 2i1. Also, the current source is producing 9A

You are on the right track -- keep going!
 

1. What is KCL in circuit analysis?

KCL stands for Kirchhoff's Current Law, which is one of the fundamental laws in circuit analysis. It states that the sum of all currents entering a node (or junction) in a circuit must be equal to the sum of all currents leaving that node.

2. How is KCL used in circuit analysis?

KCL is used to analyze the flow of current in a circuit. By applying KCL at a node, we can determine the unknown currents in the branches connected to that node. It is especially useful in solving complex circuits with multiple loops and nodes.

3. What are the assumptions made when applying KCL in circuit analysis?

The two main assumptions made when applying KCL are: 1) The circuit is in a steady state, meaning there are no changes in the circuit elements over time, and 2) The circuit is a closed loop, meaning there are no open branches or gaps in the circuit.

4. Can KCL be applied to both DC and AC circuits?

Yes, KCL can be applied to both DC (direct current) and AC (alternating current) circuits. It is a fundamental law that applies to any type of circuit, regardless of the type of current flowing through it.

5. What are some common mistakes when applying KCL in circuit analysis?

Some common mistakes when applying KCL include: forgetting to include all currents at a node, not considering the direction of currents, and not taking into account the polarity of voltage sources. It is important to carefully label all currents and their directions when applying KCL to avoid these mistakes.

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