Can I find a general solution to this circuit?

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Homework Help Overview

The discussion revolves around finding the equivalent resistance of a circuit that includes a variable number of resistors, specifically ##R_3##, and how this might relate to a general solution based on the number of these resistors.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants explore the complexity of calculating equivalent resistance in a circuit with multiple resistors and question whether a general formula can be established based on the number of ##R_3## resistors. Some suggest considering the relationship between the resistance functions R(n) and R(n+1) as a potential approach.

Discussion Status

There are multiple interpretations of how to approach the problem, with some participants suggesting methods for dealing with similar circuit configurations. A productive direction has been provided through the exploration of relationships between resistance functions.

Contextual Notes

Participants note the complexity of the calculations involved and the potential for approximations when the number of resistors becomes large. There is an emphasis on the need to simplify the circuit by temporarily removing certain components.

Lotto
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Thread moved from the technical forums to the schoolwork forums
TL;DR Summary: I have to find an equivalent resistance of the circuit below, dependent on the amount of ##R_3## - resistors.

Here is the circuit:
circuit2.jpg

I think there is no general solution. When I want to calculate it, I have to do ##((((R_1+2R_2)^{-1}+{R_3}^{-1})^{-1}+2R_2)^{-1}+{R_3}^{-1})^{-1}...##, so it is kind of crazy. Is there any general solution dependent on the amount of ##R_3## - resistors ##n##? So something like ##R_{\mathrm {eq} _n}=....##.
 
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Google "ladder circuit". You will find methods for dealing with problems like this.
 
Lotto said:
TL;DR Summary: I have to find an equivalent resistance of the circuit below, dependent on the amount of ##R_3## - resistors.

Here is the circuit:
View attachment 326155
I think there is no general solution. When I want to calculate it, I have to do ##((((R_1+2R_2)^{-1}+{R_3}^{-1})^{-1}+2R_2)^{-1}+{R_3}^{-1})^{-1}...##, so it is kind of crazy. Is there any general solution dependent on the amount of ##R_3## - resistors ##n##? So something like ##R_{\mathrm {eq} _n}=....##.
My first step would be to leave out the two R1s. Those can be put back in later.
The resistance of the remaining system is a function R(n). Can you figure out the relationship between R(n) and R(n+1)?
 
haruspex said:
My first step would be to leave out the two R1s. Those can be put back in later.
The resistance of the remaining system is a function R(n). Can you figure out the relationship between R(n) and R(n+1)?
Yes, I did it and I made an approximation when ##n## is big, so we can say that ##R_n \approx R_{n-1}##, similary as when we solve an infinite ladder circuit. Then it was easy to solve.
 

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