Can I find a general solution to this circuit?

In summary, the conversation discusses finding an equivalent resistance for a circuit with multiple ##R_3## resistors. The speaker mentions using a general solution and suggests looking up "ladder circuit" methods. They also mention a relationship between the resistance of the circuit and the number of ##R_3## resistors, making it easier to solve for large values of ##n##.
  • #1
Lotto
217
13
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}=....##.
 
Physics news on Phys.org
  • #2
Google "ladder circuit". You will find methods for dealing with problems like this.
 
  • #3
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)?
 
  • #4
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.
 

Similar threads

  • Introductory Physics Homework Help
Replies
7
Views
773
  • Introductory Physics Homework Help
Replies
28
Views
1K
  • Introductory Physics Homework Help
Replies
5
Views
1K
  • Introductory Physics Homework Help
Replies
1
Views
250
  • Introductory Physics Homework Help
Replies
3
Views
1K
  • Introductory Physics Homework Help
Replies
3
Views
599
  • Introductory Physics Homework Help
Replies
17
Views
2K
  • Introductory Physics Homework Help
Replies
4
Views
309
  • Introductory Physics Homework Help
Replies
3
Views
588
Replies
5
Views
1K
Back
Top