How Does Kirchoff’s Voltage Law Apply to Supernodes in Circuit Analysis?

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Discussion Overview

The discussion revolves around the application of Kirchhoff’s Voltage Law (KVL) and Kirchhoff’s Current Law (KCL) in analyzing a circuit involving supernodes. Participants are examining a specific example from a textbook related to finding an unknown current (IS2) in a circuit with given currents.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant presents a method using KCL to find IS2, resulting in a calculation of 4A, which contradicts the textbook answer of 1A.
  • Another participant suggests that at the junction of R1 and R2, KCL can be applied, leading to the equation IS1 + IS2 = I2.
  • A third participant notes that the equation for the supernode does not include IS2, stating that IS1 equals the sum of I3 and I5.

Areas of Agreement / Disagreement

Participants express differing approaches to applying KCL and KVL, with no consensus on the correct method or the value of IS2. The discussion remains unresolved regarding the correct application of laws in this context.

Contextual Notes

There are potential limitations in the assumptions made about the circuit configuration and the definitions of the currents involved. The participants do not clarify these assumptions, which may affect the analysis.

pekpek
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Hello All,

I am trying to teach myself basic EE. The textbook I am using gave the following example:

1. Find IS2. Diagram is attached.
Given:
IS1 = 2A
I2 = 3A
I3 = 2A
I4 = 1A
I5 = 0A

The answer in the textbook is 1A.

My Method using KCF:
IS1 + IS2 - I2- I3 - I4 -I5 = 0

Substituting the numbers I get: 2 + IS2 - 3 - 2 - 1 = 0; IS2 = 4A

I am not sure where I am going wrong here.

Thanks for any insight!
 

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At the junction of R1 and R2 applying KCL you see:
Is1 + Is2 = I2

Voila!
 
If you look at the equation for the supernode, it won't involve IS2
current in = current out

Is1 = I3 + I5

Good luck with your studies.
 
Ahhh. Thanks NascentOxygen!
 

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