Find the Thevenin's Equivalent for the following circuits

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Discussion Overview

The discussion revolves around finding the Thevenin's equivalent for specific circuits, focusing on the calculations of Thevenin resistance and voltage. Participants are sharing their solutions, seeking feedback, and addressing procedural guidelines for posting problems in the forum.

Discussion Character

  • Homework-related
  • Debate/contested

Main Points Raised

  • One participant has provided their solutions for two problems but is uncertain about the accuracy of their Thevenin voltage calculation.
  • Several participants emphasize the importance of posting each problem separately to avoid confusion, citing forum policy.
  • There is a suggestion that a sign error may have occurred in the calculation of the Thevenin voltage for the first problem.
  • A later reply confirms that with more precise calculations, the Thevenin voltage could be approximated to 20.0 V.
  • Participants express concerns about the use of external image hosting services for problem illustrations, suggesting that direct uploads are preferable to avoid broken links.

Areas of Agreement / Disagreement

Participants generally agree on the procedural guidelines for posting problems and the need for clarity in calculations. However, there is disagreement regarding the accuracy of the Thevenin voltage calculation, with some suggesting corrections while others provide alternative confirmations.

Contextual Notes

There are indications of potential errors in calculations, particularly regarding the Thevenin voltage, but these remain unresolved. The discussion also highlights the importance of adhering to posting guidelines to facilitate clearer communication.

AlphaLibrae
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Homework Statement
3) Find the Thevenin equivalent of the following circuit: i.e. find the thevenin's voltage and thevenin's resistance

4)Find the Thevenin's voltage and Thevenin's resistance for the following circuit and hence find the current through the load resistor

The problems and the circuit diagrams are here:
Relevant Equations
Kirchhoff's Laws
The current entering any junction is equal to the current leaving that junction. i2 + i3 = i1 + i4

The directed sum of the potential differences (voltages) around any closed loop is zero.
v1 + v2 + v3 +v4 = 0
I have actually already written out and solved for my own solutions to these problems, but I was wondering if I could get a second opinion on my solutions:

For Problem 3:
For Problem 4:
 
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In future, please post each problem in separate posts. This is PF policy. We find that this avoids "crosstalk" confusion when multiple people are engaged with different problems in the same thread.

For your first problem the Thevenin resistance looks okay but the Thevenin voltage does not. I think you've dropped a sign when solving for ##i_2##.
 
gneill said:
In future, please post each problem in separate posts. This is PF policy. We find that this avoids "crosstalk" confusion when multiple people are engaged with different problems in the same thread.

For your first problem the Thevenin resistance looks okay but the Thevenin voltage does not. I think you've dropped a sign when solving for ##i_2##.

Ah ok, so would it actually be 15 + (6)(0.83 = 19.98 V?
 
AlphaLibrae said:
Ah ok, so would it actually be 15 + (6)(0.83 = 19.98 V?
Yes. With a few more digits used for intermediate values you'd find out that it comes out to 20.0 V.
 
gneill said:
In future, please post each problem in separate posts.
... and please upload photos instead of link to another provider, because otherwise it happens what just [2/22/20 - 1426 GMT] happened: "imgur refuses to connect" or the link will be broken long term!
 
fresh_42 said:
... and please upload photos instead of link to another provider, because otherwise it happens what just [2/22/20 - 1426 GMT] happened: "imgur refuses to connect" or the link will be broken long term!
Can't see a thin.
 

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