Circuit Analysis: Solving for Req of 10 Ohms

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Discussion Overview

The discussion revolves around solving for the equivalent resistance (Req) of a circuit involving multiple resistors, specifically aiming to understand how the total resistance can be calculated to arrive at a value of 10 ohms. The context includes homework-related problem-solving and circuit analysis.

Discussion Character

  • Homework-related
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant expresses confusion about how the equivalent resistance is calculated to be 10 ohms, suggesting that some resistors may short circuit, leading to a different total resistance of 14 ohms.
  • Another participant asserts that the 12 ohm resistor is short-circuited and prompts others to analyze the configuration of the 6 ohm resistors to determine if they are in series or parallel.
  • A different participant claims that the 6 ohm resistor at the top right can be disregarded because it is shorted by a wire, implying a change in the circuit's configuration.
  • One participant proposes a method of calculating the equivalent resistance by changing the configuration of the resistors after removing the 12 ohm resistor, suggesting that the remaining resistors can be simplified to find the total resistance.
  • Another participant comments on the complexity of the problem, noting that under exam conditions, it may be challenging to think clearly and achieve a high score.
  • One participant concludes that the equivalent resistance of the circuit is 10 ohms, based on their calculations involving the parallel arrangement of the resistors.

Areas of Agreement / Disagreement

Participants express differing views on the configuration of the resistors and how to approach the calculation of the equivalent resistance. There is no consensus on the correct method or final answer, as various interpretations of the circuit layout are presented.

Contextual Notes

Participants mention assumptions about short-circuiting resistors and the arrangement of resistors in series or parallel, but these assumptions are not universally accepted, leading to different calculations and interpretations of the circuit.

planauts
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Homework Statement



Image: http://puu.sh/1ejYb
http://puu.sh/1ejYb


Homework Equations


Req of n resistors in series = R1 + R2 + ... + Rn
Req of n resistors in parallel = 1/R1 + 1/R2 + ... + 1/Rn

The Attempt at a Solution



The answer is supposed to be 10 ohms. However, I don't know how they got that.

What I was thinking that some of the resistors short circuit and the current does not pass through them. So, it would be like: 3 ohms, then 6 ohms and finally 5 ohms. However, that adds up to 14 ohms and also I'm very sure that's wrong.

Thanks a lot!
 
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It is clear that the 12 ohm resistor short circuit. Now try to see whether the 6 ohm resistor on the right in the upper line and the 6 ohm resistor in the bottom line are in series or parallel.
 
The 6Ω resistor in the right at top can be ruled out i think.. bcuz even that is shorted by a wire from the junction of 5Ω and 6Ω resistors at the bottom.
 
PhysicoRaj - I don't think that's correct.

After removing the 12 Ohm..

The 6 Ohm at the top right is in parallel with the 6 Ohm at the bottom. So delete the 6 Ohm at top right and change the 6 Ohm at the bottom to 3 Ohm.

Then the new 3 Ohm just created is in parallel with the remaining 6 Ohm making 2 Ohms.

At this point you have 3, 2 and 5 in series.
 
This is a creative problem. Under examination pressures, where it is often difficult to get ones thoughts clear, there may not be a high score rate on this question.
 
12Ω resistor is short cirrcuit. three 6Ω are parallel.
So, equivalent resistor of circuit is 3+6/3+5=10Ω
 

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