Find the Thevenin resistance for network with dependent current source

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Discussion Overview

The discussion revolves around finding the Thevenin resistance of a circuit that includes a dependent current source. Participants explore the implications of the dependent source on the analysis and express uncertainty regarding the definition of a specific current variable, denoted as "i".

Discussion Character

  • Homework-related
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant expresses uncertainty about how to approach the problem due to the presence of the dependent current source (49i), noting that simply silencing the voltage source does not yield the expected resistance.
  • Another participant questions where the current "i" is defined within the circuit, suggesting it may relate to the non-load aspects of the circuit.
  • There is a discussion about whether the dependent current source can be treated as part of the load or if it should be open-circuited to analyze the circuit.
  • One participant clarifies that the dependent current source generates a current of 49 times "i", indicating that identifying "i" is crucial for solving the problem.
  • Another participant suggests that once the location of "i" is determined, the rest of the problem may become straightforward, mentioning the need to find both the open circuit voltage and the short circuit current to determine the Thevenin resistance.
  • There is speculation about whether it is possible to find "I" without a specific definition provided, with concerns that the professor may have omitted necessary information.
  • One participant asserts that the problem cannot be solved without knowing what current "i" represents.
  • Another participant inquires about the professor's provided answer for R(Th) and whether it could be used to deduce "I" if additional information was given.
  • There is a suggestion to explore all possible locations for "i" to see which configuration aligns with the provided R(Th).

Areas of Agreement / Disagreement

Participants generally agree that the definition of the current "i" is critical to solving the problem, but there is no consensus on how to proceed without this information. Multiple competing views on the treatment of the dependent current source and the implications of "i" remain unresolved.

Contextual Notes

Participants note the potential missing information regarding the current "i" and its definition, which may affect the ability to solve the problem accurately. The discussion reflects uncertainty about the correct approach to analyze the circuit with the dependent source.

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Homework Statement

http://imageshack.us/a/img15/7218/sg2prob11.jpg
Find the Thevenin resistance for the network(Sorry for the bad drawing, but that is a point like point / node A on the bottom where it's going out too and likely part of the load too, with a wire connected to the circuit, I'll see if I can draw it better when I get home)

Homework Equations



V = IR

KVL, KCL,

voltage division, current division

Thevenin procedures, etc

The Attempt at a Solution



I'm not sure how to approach this problem, because of that dependent current source (49i). Apparently you can't just silence the voltage source and then take the resistance from point a to the bottom point (which would've just been 96.7 ohms).

Any tips?
 
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Where is the current i defined?
 


I'm not too sure about that either, but it would probably have to do with the non-load in the circuit?


Or can you take that dependent current source as part of the load too? Or just cut it out of the wire (open-circuited) ?? (Where I guess the current i would then be in the rest of the circuit)
 
Last edited:


Apparently the dependent current source generates a current of 49 times i, where i is a current somewhere else in the network. i could be the current in either of the resistors, for example. You need to find out where i is.
 


Once you figure out where the current for the dependent source is defined in the circuit the rest of the problem should be pretty straight forward.

To find find the Thevenin resistance looking into the terminals you must first find the open circuit voltage and the short circuit current.
 


So is it possible to find an 'I' or is it impossible without an 'I' specifically given.

(My professor wrote up this problem and it's possible he forgot to put this on the problem and he's done it before)
 


You can't solve the problem with knowing what current is represented by "i".
 


He gave the answer to R(Th) though, would it be possible to solve for I then?
 


What did he give? Did he also give Vth? It would probably be possible to work the problem with all possible locations for i and see which one gave the Rth you prof gave you.
 

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