- #1
Current flow in a two source circuit
- Thread starter xJJx
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- Circuit Current Current flow Flow Source
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Discussion Overview
The discussion revolves around understanding current flow in a two-source circuit, focusing on the interpretation of current directions and the application of loop current analysis. Participants explore the implications of multiple current sources and how to approach solving for currents in such circuits.
Discussion Character
- Exploratory
- Technical explanation
- Conceptual clarification
- Debate/contested
- Homework-related
Main Points Raised
- One participant seeks clarification on whether their understanding of current flow in a two-source circuit is correct, specifically regarding the direction of current flow.
- Another participant questions the method of determining the current of a voltage source without knowing resistance values.
- Some participants suggest that current does not flow in certain loops based on their definitions of loop currents.
- There is a discussion about the necessity of treating loop currents as separate for the purpose of solving circuit equations, despite the possibility of currents interacting in shared components.
- A participant expresses confusion about the concept of currents being confined to their respective loops and questions if this is a standard assumption in analyzing two-source circuits.
- Another participant emphasizes that the number of sources or loops does not change the fundamental approach to drawing and solving for loop currents.
Areas of Agreement / Disagreement
Participants exhibit a mix of agreement and disagreement. While some agree on the necessity of treating loop currents as separate for analysis, others challenge the implications of this approach and express confusion about its application in practice. The discussion remains unresolved regarding the clarity of these concepts.
Contextual Notes
Participants note limitations in their understanding, particularly regarding the lack of knowledge about solving current loops and the assumptions made in circuit analysis. There is also mention of the need for specific resistance values to fully analyze the circuit.
Who May Find This Useful
This discussion may be useful for students preparing for university-level physics or electrical engineering courses, particularly those interested in circuit analysis and the behavior of currents in multi-source circuits.
- #2
berkeman
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Can you post a better version of your picture? Take it without any shadows over the paper, and rotate and process it a bit to make it easy to read.
- #3
- #4
berkeman
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Thanks. The circuit might be okay, but how are you setting the current of the left voltage source to 5A? What are the values of the resistances?
- #5
xJJx
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Hi, thanks for your reply :) The question doesn't tell me the resistance values, it just tells me everything stated on the picture. I thought current travels from positive terminals to negative, so I guessed the current flow directions to be like this ^. Is this correct?berkeman said:
- #6
cnh1995
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Partly.xJJx said:
Pink current doesn't flow in the right loop and green current doesn't flow in the left loop.
- #7
xJJx
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haha I read that in Sheldon's voice & please may you explain why?cnh1995 said:
- #8
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When you define loop current they should be confined to individual loops. This doesn't mean part of each current doesn't flow in the other loop but you can't solve for values without specific loop currents.xJJx said:
- #9
cnh1995
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You have 5A flowing from the battery (pink) and 6A through the middle resistor. So, the remaining 1A (green) must be supplied by the rightmost current source. Hence, both 5A and 1A are confined to their respective loops. They add up in the middle branch and again split at the bottom node such that the pink current flows back to the battery and the green current flows back to the current source.xJJx said:
- #10
xJJx
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But even if the two currents are confined to their respective loops, that still doesn't mean part of them can't flow in the other loops. So I still don't understand why they don't split at the bottom junction.cnh1995 said:
- #11
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Yes, that's exactly what I said in post #8xJJx said:
You PRETEND that they are totally separate currents so that you can solve for them, Again, this is what I already explained in post #8. What is it about that that is not clear? How would YOU solve for values if you mix everything up the way you seem to want to? Do you understand how to solve current loops?
- #12
xJJx
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No, I haven't learned how to solve current loops. I haven't started university yet, I'm trying to learn this stuff before uni starts. I know how current flows in a single-source circuit, but not in a two-source circuit.phinds said:
- #13
xJJx
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Is the 'currents confined to their respective loops' thing just an assumption we make for determining the loop currents in the circuit? do we ALWAYS make this assumption for two-source circuits, even when we're not trying to determine loop currents?phinds said:
- #14
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The number of sources is irrelevant and the number of loops is irrelevant. You draw a single current around each loop, write the resulting equations, and solve. Elements that are common to two loops have a current which is the sum/difference of the two loop currents. Assumed direction of the loop currents is irrelevant. If you've made the "wrong" assumption you just get a negative answer.xJJx said:
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