1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Resistor value

  1. Jan 25, 2009 #1
    resistor value ....

    1. The problem statement, all variables and given/known data
    power.JPG
    see the attached diagram

    2. Relevant equations

    What value of resistor in the place of the 33 ohm resistor would draw maximum power from the rest of the circuit and what power would it draw?

    3. The attempt at a solution

    I can figure out the currents flowing in different branches of the circuit using maxwell mesh network analysis. But I did not have a clue of how to solve the problem. I know what power dissipation is and how to work it out, but the given question is giving me headaches.
     
    Last edited: Jan 25, 2009
  2. jcsd
  3. Jan 26, 2009 #2
    Re: resistor value ....

    somebody help.....please
     
  4. Jan 26, 2009 #3

    MATLABdude

    User Avatar
    Science Advisor

    Re: resistor value ....

    Nobody can see your attachment yet, pending administrator approval. You could always host it somewhere else, and then link to it.
     
  5. Jan 28, 2009 #4

    MATLABdude

    User Avatar
    Science Advisor

    Re: resistor value ....

    Ah, your attachment has been approved!

    I don't know if you're still looking for help or not, but I'll guide you a bit:

    1) Under what load conditions does maximum power transfer occur?

    2) How would you black box the rest of the circuit, making it a block that you could attach this resistor to?

    EDIT: For future reference, you may want to host your picture elsewhere and post a link, instead of waiting for moderator approval.
     
  6. Jan 28, 2009 #5
    Re: resistor value ....

    MATLABdude first thanks for the reply,

    I know that the maximum power transfer occurs when the load resistance is equal to that of the voltage source internal resistance.

    Are you saying that looking from the 33ohm resistor point of view and calculating the total resistance of all the resistor(not including 33ohm resistor) and hence that will be the valueof the resistor that the 33 ohm resistor should be?
    Do you mean to calculate the total resistance(obviously ommiting 33 ohm resistor) by replacing the batteries with short circuits. It sounds like thevenin problem or is it?
     
  7. Jan 28, 2009 #6

    MATLABdude

    User Avatar
    Science Advisor

    Re: resistor value ....

    My job here is done!

    (But strictly speaking, you should also have an equivalent voltage in a Thevenin equivalent, even though you don't need it for this question).
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?