Find the equivalent resistance of this circuit w/o Data?

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Discussion Overview

The discussion revolves around finding the equivalent resistance of a circuit between points a and b without specific numerical data. Participants explore various methods for solving the problem, including the use of series and parallel combinations of resistors.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • Some participants express uncertainty about how to approach the problem without numerical values, suggesting that using variables may not be straightforward.
  • Others propose that since all resistors are equal to "R," it should simplify the calculations using series and parallel combinations.
  • One participant indicates that the answer will likely be expressed in terms of R, such as "7R" or "19R/5."
  • There are multiple attempts to clarify the circuit configuration and how to combine resistors, with some participants providing their calculations and others questioning the correctness of those calculations.
  • Participants discuss the difficulty of accessing the circuit diagram due to issues with image hosting, leading to confusion about the circuit layout.
  • One participant shares their calculated equivalent resistance as "6R," but this is challenged by others who suggest that the calculation may be incorrect based on the circuit configuration.
  • There are suggestions to break down the circuit into smaller parts for easier analysis, with specific recommendations on how to combine resistors step-by-step.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correct approach or the equivalent resistance value. There are competing views on how to combine the resistors and uncertainty about the calculations presented.

Contextual Notes

Some participants express confusion regarding the circuit layout and calculations, indicating that assumptions about the arrangement of resistors may not be clear. There are unresolved mathematical steps in the proposed solutions.

nicholasrivera
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Homework Statement


Find the equivalent resistance of this circuit between points a and b
https://imgur.com/a/LWcIC
upload_2018-2-22_13-56-22.png

Homework Equations



The Attempt at a Solution


I am not sure how to complete this problem without any variables. I tried replacing the numbers with the variables which is what I think your supposed to do but It still isint making sense.
 

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nicholasrivera said:

Homework Statement


Find the equivalent resistance of this circuit between points a and b

Homework Equations


http://tinypic.com/r/33mn1gl/9

The Attempt at a Solution


I am not sure how to complete this problem without any variables. I tried replacing the numbers with the variables which is what I think your supposed to do but It still isint making sense.
I'm not sure what you mean about "without any data". Can you just solve the question using series & parallel combinations of resistors? Since they are all equal to "R" in value, that makes it pretty easy...
 
berkeman said:
I'm not sure what you mean about "without any data". Can you just solve the question using series & parallel combinations of resistors? Since they are all equal to "R" in value, that makes it pretty easy...
But I am not sure what I am supposed to get as an answer will it just be in terms of R?
 
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nicholasrivera said:

Homework Equations


http://tinypic.com/r/33mn1gl/9
When I go to that link, I don't get anything related to electronics. Mostly just ads.
 
The answer you are looking for will be in terms of the resistance R. In other words it will be something like 7*R or 19*R/5, or something like that. Try using series/parallel combinations to reduce the resistance between a and b to a single resistor.
 
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nicholasrivera said:
will it just be in terms of R?
Yes. If there were just 2 resistors in series, the answer would be "2R". If there were just 2 resistors in parallel, the answer would be "R/2". Right?
 
.Scott said:
When I go to that link, I don't get anything related to electronics. Mostly just ads.
I get a small schematic mixed in with the ads for a few seconds, and then a sea of ads washing out the schematic... Annoying...
 
.Scott said:
When I go to that link, I don't get anything related to electronics. Mostly just ads.
sorry used a terrible image hosting site I fixed the link https://imgur.com/a/LWcIC
 
nicholasrivera said:
sorry used a terrible image hosting site I fixed the link https://imgur.com/a/LWcIC
Thanks. Now can you show us your work step-by-step to do the series & parallel combinations we are suggesting? :smile:
 
  • #10
berkeman said:
Thanks. Now can you show us your work step-by-step to do the series & parallel combinations we are suggesting? :smile:
https://i.imgur.com/ubVARZs.jpg there's my answer I got 6R but I am not sure if I combined the resistors correctly.​
 
  • #11
nicholasrivera said:
I got 6R
That can't be right, since if the middle parallel resistor were not there, the other resistors would add up to 5R.

The sideways image is a bit hard to read. Can you just type your work into the forum window please?
 
  • #12
Sorry I Labeled it as following R1 and R2 are the top in series R3 R4 are the two middle ones in parallel and R5 and R6 are the bottom two in series. I did R12= 2R
R34= (1/R+1/R)-1
R56=(1/R+1/R)-1
R123456= (1/4R + 1/2R)-1
 
  • #13
nicholasrivera said:
Sorry I Labeled it as following R1 and R2 are the top in series R3 R4 are the two middle ones in parallel and R5 and R6 are the bottom two in series. I did R12= 2R
R34= (1/R+1/R)-1
R56=(1/R+1/R)-1
R123456= (1/4R + 1/2R)-1
No, that doesn't look right, and I honestly am not following what you are doing.

Start by combining the right-hand 3 resistors into one. What is the value of those 3 series "R" resistors? And now, is that combined resistance in parallel with anything?
 
  • #14
nicholasrivera said:
I Labeled it as following R1 and R2 are the top in series R3 R4 are the two middle ones in parallel and R5 and R6 are the bottom two in series.
Okay. So...
R1 is between nodes A and C.
R3 is between nodes C and D.
R5 is between nodes B and D.
And @berkeman is asking you to find the combined resistance or R2, R4, and R6.
 
  • #15
You are taking a bad turn in you approach. The first thing you should do is to collapse the loop on the right to a single resistance between C and D. After that, you will have a simple problem of 3 resistances in series. Branching nodes are always a problem and you should first work on small parts toward an equivalent problem that replaces the branches with a simpler diagram.
 

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