Solve Circuit for R(ab): Equivalent Resistance 20 Ohms?

  • Context: Engineering 
  • Thread starter Thread starter jonathan.15
  • Start date Start date
  • Tags Tags
    Circuit
Click For Summary

Discussion Overview

The discussion revolves around finding the equivalent resistance R(ab) in a circuit, with participants questioning whether the circuit is open or if current can flow between points A and B. The scope includes conceptual understanding and circuit analysis.

Discussion Character

  • Conceptual clarification, Debate/contested, Technical explanation

Main Points Raised

  • One participant suggests that the circuit is open and therefore the resistance should be infinite, questioning the provided answer of 20 ohms.
  • Another participant counters that there are multiple paths for current to flow from A to B, implying that the resistance is not infinite.
  • A different participant reiterates the belief that the absence of a wire connecting A and B indicates an open circuit with infinite resistance.
  • One participant expresses understanding after further analysis, noting that the current can indeed flow from A to B despite initial assumptions of separation.

Areas of Agreement / Disagreement

Participants exhibit disagreement regarding the nature of the circuit, with some believing it to be open and others asserting that current can flow, leading to the conclusion of a finite resistance.

Contextual Notes

There are unresolved assumptions about the circuit's configuration and the definitions of open and closed circuits, which affect the interpretation of resistance.

jonathan.15
Messages
9
Reaction score
0
ImageUploadedByPhysics Forums1391875387.022416.jpg


The question asks to find the Equivalent resistance R(ab) for the circuit. Is this a trick question? Because I thought it is an open circuit and therefore the resistance between a and b would be infinite. The answer in the book is 20 ohms, please explain if possible
 
Physics news on Phys.org
Why do you think the resistance is infinite? There are lots of ways the current can flow from a to b.

You can solve this by picking off pairs of resistors that are in series and parallel, and replacing then with a single resistor. You will end up with just one resistor connecting a and b.
 
Because there is no wire connecting points A and B I thought this is an open circuit, which has infinite resistance?
 
ImageUploadedByPhysics Forums1391880549.364392.jpg


This is my final step in reducing the circuit, so now this makes sense that the resistance would be 20, I kept thinking that current would not flow flow from a down to b because they were separated but they are connected
 
Moderator's note: thread moved from Electrical Engineering.
 

Similar threads

Replies
5
Views
4K
Replies
15
Views
3K
  • · Replies 17 ·
Replies
17
Views
13K
Replies
6
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 20 ·
Replies
20
Views
5K
  • · Replies 42 ·
2
Replies
42
Views
6K
  • · Replies 8 ·
Replies
8
Views
5K