Find the Current and potential difference in a parallel/series circuit

Click For Summary

Homework Help Overview

The discussion revolves around analyzing a circuit with both series and parallel resistors to determine the current through a specific resistor and the potential difference between two points. The circuit includes resistors of various values, specifically a 20 ohm resistor.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster presents two different interpretations of the circuit configuration and calculations for the total resistance. Participants discuss the arrangement of resistors in series and parallel, questioning the assumptions made in each approach.

Discussion Status

Some participants have provided feedback on the original poster's attempts, indicating that one of the interpretations is more aligned with the correct approach. There is acknowledgment of the need for clarity regarding units in calculations.

Contextual Notes

The original poster expresses uncertainty about their calculations and seeks validation of their reasoning. There is mention of a figure that was initially inaccessible, which may have contributed to confusion in the problem setup.

Absolutism
Messages
27
Reaction score
0

Homework Statement



Okay. I got two different answers for these and I don't know which one is right so I could continue from there. If you will please help by letting me know which answer is right and why, I'd very much appreciate it.

This is the figure:
http://www.webassign.net/pse/p28-09alt.gif
where R = 20ohm

1. Find the current in R (20ohm resistor)
2. Find the potential difference between points a and b

Homework Equations



-

The Attempt at a Solution



Answers I got:

One says that the first 3 resistors on the top are all in parallel, and then the total of that is in series with the other two that have 20 and 5 ohm, so the total is 27.5

The other answer is that in the resistor at the very top, the current goes through the wire then meets a junction and separates into say, i1, i2, i3 and then they all meet again at the junction near point a. So the bottom 2 resistors are in series, but then the total of that and the two resistors above it are all in parallel, then in series with the very top one.
So we have 1/25+1/10+1/5
then r= 2.94
added to 10
so 12.94

If you could please let me know which one is on the right track, I'd appreciate it.
 
Physics news on Phys.org
Your second version is on the right track, and the value you obtained for the total equivalent resistance is good (although units are not specified. Always specify units!).
 
Okay. Thank you so much. I'll continue it now. I thought I was making stuff up at some point!
 

Similar threads

  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 3 ·
Replies
3
Views
921
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
Replies
20
Views
2K
  • · Replies 14 ·
Replies
14
Views
2K
Replies
4
Views
2K
Replies
10
Views
1K
  • · Replies 30 ·
2
Replies
30
Views
3K
  • · Replies 5 ·
Replies
5
Views
1K