AC Maximum Power Transfer question

Click For Summary

Discussion Overview

The discussion revolves around determining the values of a resistor and a capacitor in a load impedance configuration to achieve maximum power transfer in an AC circuit. The context includes both theoretical and practical considerations related to impedance matching in parallel circuits.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant suggests that if the components in the load impedance were in series, the series impedance must equal the conjugate of the load impedance, indicating a method for finding solutions.
  • Another participant confirms that the complex impedance of the load must be the complex conjugate of the source impedance and prompts for the value of the source impedance.
  • A participant calculates the source impedance as 20 + jωL, concluding that the load impedance should be 20 - 10j, and questions if this can be equated to the parallel combination of the resistor and capacitor.
  • Another participant reassures that the previous assumption is correct and encourages further simplification of the equations involved.
  • A later reply expresses understanding and appreciation for the assistance received in the discussion.

Areas of Agreement / Disagreement

Participants appear to agree on the method of using complex conjugates for impedance matching, but there is some confusion regarding the calculations and the specifics of the parallel combination of components. The discussion remains somewhat unresolved as participants seek clarification on certain steps.

Contextual Notes

There are indications of confusion regarding the calculations of current and voltage across the components, as well as the specifics of the parallel impedance formula. The discussion does not fully resolve these uncertainties.

kozis
Messages
11
Reaction score
0

Homework Statement



In the circuit attached the load impedance ZL comprises a resistor in parallel with a capacitor. Determine the value of the resistor and the capacitor to ensure that the maximum power is received by the load impedance.


The Attempt at a Solution


So,if components in ZL were in series i would say that the series impedance must be equal with the conjugate of ZL take real parts and imaginary parts separately and easily find the solutions.I think so,so correct me if I am wrong. But now I don't know what to do. I thougt that i could find the current through ZL and then the Voltage so resistor and capacitor would have same voltage across them,but with the current through each of them being different and unknown how I could calculate them?
 

Attachments

  • Untitled.jpg
    Untitled.jpg
    6.6 KB · Views: 537
Last edited:
Physics news on Phys.org
kozis said:

Homework Statement



In the circuit attached the load impedance ZL comprises a resistor in parallel with a capacitor. Determine the value of the resistor and the capacitor to ensure that the maximum power is received by the load impedance.


The Attempt at a Solution


So,if components in ZL were in series i would say that the series impedance must be equal with the conjugate of ZL take real parts and imaginary parts separately and easily find the solutions.I think so,so correct me if I am wrong. But now I don't know what to do. I thougt that i could find the current through ZL and then the Voltage so resistor and capacitor would have same voltage across them,but with the current through each of them being different and unknown how I could calculate them?

You are on the right track that the complex impedance of Zl has to be the complex conjugate of the source impedance (the series R & L). What is the value of Zs? And write the impedance of a parallel RC circuit for Zl. Can you then match up components in a conjugate fashion?
 
Value of Zs should be 20 + jωL which comes up to be 20+10j so the impedance of ZL must be 20 -10j right? Is it correct to assume that this must be equal to the parallel combination, eg. ZcZR/Zc+Zr? I am a bit confused!
 
kozis said:
Value of Zs should be 20 + jωL which comes up to be 20+10j so the impedance of ZL must be 20 -10j right? Is it correct to assume that this must be equal to the parallel combination, eg. ZcZR/Zc+Zr? I am a bit confused!

That's correct. No need for confusion!

So now just do the substitutions into your last equation and simplify it into the form a+bi and equate...
 
yeah I can see it now..Thanks a lot !
 

Similar threads

  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 13 ·
Replies
13
Views
2K
  • · Replies 2 ·
Replies
2
Views
4K
Replies
11
Views
3K
  • · Replies 16 ·
Replies
16
Views
5K
  • · Replies 4 ·
Replies
4
Views
2K