Solve Rth for Circuit | Get Expert Help Now

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Discussion Overview

The discussion focuses on finding the Thevenin resistance (Rth) for a specific electrical circuit. Participants explore the implications of omitting certain resistors and the correct procedure for calculating Rth, engaging in a homework-related context.

Discussion Character

  • Homework-related
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant suggests that R3 can be omitted and that R1, R2, and R4 are in series, proposing an Rth of 10k Ohms.
  • Another participant counters that R3 cannot be omitted as it is essential for the current path from A to B.
  • A participant questions the procedure for finding Thevenin resistance, particularly regarding the impact of replacing the voltage source with a wire.
  • There is a discussion about whether R5 can be eliminated, with one participant confirming that shorting the voltage source allows for R5 to be disregarded.
  • One participant proposes that R1 and R4 are in series, with that combination in parallel to R2, and then in series with R3, leading to a calculated Rth of 5.4 k Ohms.
  • Another participant agrees with the calculation of Rth as 5.4 k Ohms, expressing satisfaction with the resolution of the problem.

Areas of Agreement / Disagreement

Participants express disagreement regarding the treatment of R3 and R5 in the circuit analysis. While there is some agreement on the final calculation of Rth as 5.4 k Ohms, the discussion reflects uncertainty and differing interpretations of the circuit configuration.

Contextual Notes

Participants exhibit confusion regarding the roles of R3 and R5 in the circuit, indicating a potential lack of clarity in the assumptions made about the circuit's configuration and the procedure for calculating Thevenin resistance.

GBA13
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Homework Statement


Hi,

I am trying to find Rth for this circuit but I am not sure if I've got it right, could someone give a hand?

Homework Equations

The Attempt at a Solution


I think R3 can be omitted and R1, 2, and 4 are in series so the answer is 10k Ohms as R5 is in parallel to what was the power source (now a wire) can be omitted as well?

Thanks!
 

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R3 cannot be omitted as there is no path from A to B that can avoid it.

What's the procedure for finding the Thevenin resistance of a circuit?
 
Really? I thought that when Vt has been replaced by a wire (as you do to fine Rth) then all the current can go through the new wire instead?
 
Inject a current at A and show how it can get to B without passing through R3. Shorting the voltage supply (replacing with a wire) does not make a difference there. It does, however, let you eliminate another resistance...
 
Oh sorry, I'm getting confused with R5. (You can get rid of R5 can't you?)
 
GBA13 said:
Oh sorry, I'm getting confused with R5. (You can get rid of R5 can't you?)
Yup. Suppressing the voltage source shorts out R5, so their combined resistance is 0 Ohms.
 
So then R1 and R4 are in series and that pair is in parallel to R2. That whole combination is then in series with R3 to make Rth 5.4 k Ohms? :)
 
GBA13 said:
So then R1 and R4 are in series and that pair is in parallel to R2. That whole combination is then in series with R3 to make Rth 5.4 k Ohms? :)
Yes! :approve:
 
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gneill said:
Yes! :approve:

Yay! Thanks very much! :D
 

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