What is the Thevenin resistance in this circuit with a changable resistor?

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Homework Help Overview

The discussion revolves around a circuit involving a variable resistor and the application of Thevenin's theorem in the context of maximum power transfer. The original poster is seeking to understand how to determine the Thevenin resistance when the load resistance is variable.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants suggest looking into the maximum power transfer theorem and Thevenin's theorem. The original poster expresses difficulty in applying the theory to their specific problem and questions how to compute Thevenin resistance when not all resistors are known.

Discussion Status

Some participants have provided links to resources and guidance on the maximum power transfer theorem, while the original poster is still grappling with the application of these concepts to their circuit. There is an ongoing exploration of how to compute Thevenin resistance in the context of the given circuit.

Contextual Notes

The original poster has indicated a lack of familiarity with the relevant theorems and is seeking clarification on how to proceed with the problem, particularly regarding the known and unknown resistances in the circuit.

diredragon
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Homework Statement


In the picture below, is a circuit of constant direct current. The receiver is made of a changable resistor with resistance R. If the reciever delivers maximum electrical power its resistance is
a)9 b)6 c)3 d)1.5 e)0.5

Homework Equations


Im having trouble finding the equation for this

The Attempt at a Solution


I can't find the theory of this curcuit, the equations that fit so can you guide me a little in any way that could help?
 

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Look up 'maximum power transfer theorem'. Are you familiar with the Thevenin's theorem?
 
cnh1995 said:
Look up 'maximum power transfer theorem'. Are you familiar with the Thevenin's theorem?
I am not but i will check it out now then try to apply something to the problem and get back to you :)
 
diredragon said:
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/thevenin.html
I read about it from here but am having hard time understanding how ti apply it to my problem.
For maximum power transfer, the load resistance should be equal to the Thevenin resistance of the circuit viewed from the load terminals. Here, your load resistance is the variable resistor. Can you proceed with this?
 
cnh1995 said:
For maximum power transfer, the load resistance should be equal to the Thevenin resistance of the circuit viewed from the load terminals. Here, your load resistance is the variable resistor. Can you proceed with this?
Is the equation for thevenin resistance the one in the picture uploaded? If so how to get it if not all three resistors are known?
 

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diredragon said:
If so how to get it if not all three resistors are known?
For computing Thevenin resistance seen from the load terminals, you should remove the load resistance (variable resistance) and compute the resistance of the circuit seen from the load terminals.
 

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