Why Does the Maximum Power Transfer Theorem Yield a Negative Resistance?

[prashantgolu]

i was solving one question...it said find out value of r in a circuit so that the 6 ohm resistor consumes maximum power...i applied max power theorem ...and calculated the thevenin eqivalent resistance accrss 6 ohm resistance...and put it equal to 6...but the r cam eout to be negative...so wat to conclude from this...

 

[MATLABdude]

It would help if you posted a diagram of the circuit in question. If this is an ideal source in series with a source resistance and the 6 ohm resistor, then this question is best answered by thinking about the following question:

What is the max power transfer theorem?

I suspect a Mod will be by shortly to move this question, but homework questions like these should be posed in the Homework section:
https://www.physicsforums.com/forumdisplay.php?f=152

 

[prashantgolu]

yes...its just an ideal source...some resistances and a 6 ohm resistance...i just removed it and found out thevenin equivalent across its terminals...and compared it to be 6 for max theorem..i am attaching a file

 

[MATLABdude]

As you surmise, max power transfer happens when the load resistance is equal to the source resistance. Have you determined the Thevenin equivalent of the circuit connected to the 6 ohm resistor (i.e. everything to the left of that resistor)?

 

[DeeNos]

The maximum power transfer theorem states that in a circuit, the maximum amount of power is transferred to a load when the load's resistance is equal to the source's internal resistance. In this case, the load is represented by the 6 ohm resistor and the source's internal resistance is represented by the variable r.

Based on your calculations, it seems that the value of r that results in the maximum power being transferred to the 6 ohm resistor is a negative value. This may indicate that the circuit is not designed to operate at maximum power transfer. It is important to note that the maximum power transfer theorem is a theoretical concept and in practical circuits, there may be other factors that affect the power transfer.

In order to determine the appropriate value of r in this circuit, it may be necessary to consider other factors such as the voltage and current limitations of the components, as well as the overall design and purpose of the circuit. It is also possible that there may be errors in the calculations or assumptions made in applying the maximum power transfer theorem. Further analysis and experimentation may be needed to accurately determine the optimal value of r for this circuit.