Kirchhoff's rule for circuit with two batteries

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Homework Help Overview

The discussion revolves around a circuit problem involving Kirchhoff's rules and the implications of connecting two unequal ideal voltage sources. Participants are exploring the physical realities and theoretical constraints of such configurations.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants attempt to understand the implications of a contradiction arising from applying Kirchhoff's rules to the circuit. Questions are raised about the physical reality of having no solution and whether it indicates the absence of current.

Discussion Status

The discussion is active, with participants providing insights into the nature of the problem and clarifying the invalidity of certain circuit configurations. There is a recognition of the implications of ideal voltage sources and the concept of a short circuit.

Contextual Notes

Participants note that connecting unequal ideal voltage sources in parallel is considered an invalid connection in circuit theory, which is central to the discussion.

QuantumRose
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Homework Statement
I found a difficulty solving the following question using Kirchhoff's rules.
Relevant Equations
Kirchhoff's rules.
242850
 
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QuantumRose said:
Problem Statement: I found a difficulty solving the following question using Kirchhoff's rules.
Relevant Equations: Kirchhoff's rules.

View attachment 242850
Correct. The solution is: There is no solution.

To confirm this"
Taking the "outer" loop, in a clockwise direction (The loop containing only the 10V and 5V sources.) gives you:

10V − 5V = 0.

That's a contradiction.
 
SammyS said:
Correct. The solution is: There is no solution.

To confirm this"
Taking the "outer" loop, in a clockwise direction (The loop containing only the 10V and 5V sources.) gives you:

10V − 5V = 0.

That's a contradiction.
That's the thing that bothers me a lot. What is the physical reality that corresponds to no solution? does that mean no current anywhere or what?
 
QuantumRose said:
That's the thing that bothers me a lot. What is the physical reality that corresponds to no solution? does that mean no current anywhere or what?
No. It's a physically impossible situation if those are "ideal" sources of voltage. ##I_1 \to \infty## and ##I_3 \to -\infty## .

It's much like a short circuit.
 
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SammyS said:
No. It's a physically impossible situation if those are "ideal" sources of voltage. ##I_1 \to \infty## and ##I_3 \to -\infty## .

It's much like a short circuit.
Thank you!
 
This is one of the invalid connections in circuit theory. You can't connect two unequal ideal voltage sources in parallel and two unequal ideal current sources in series.
 
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cnh1995 said:
This is one of the invalid connections in circuit theory. You can't connect two unequal ideal voltage sources in parallel and two unequal ideal current sources in series.
This clears my mind, thank you
 
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