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Basic circuit question

  1. Nov 4, 2014 #1
    1. The problem statement, all variables and given/known data
    Find a resistance, RL, to replace R3, that will draw maximum power from the sources

    2. Relevant equations

    3. The attempt at a solution
    Am I correct in saying if I set R3 to be Rth of the whole circuit, it would draw maximum power?

    I calculated based on that
    1/(1/(120+680) +1/(820+330)) = 471.1 Ohm Rth

    I am not sure if I should have included the 100Ohm resistor(R3) in the calculation or not.

    Attached Files:

  2. jcsd
  3. Nov 4, 2014 #2


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    Staff: Mentor

    R3 = Rth should work.

    The 100Ω is not part of these calculations.
  4. Nov 4, 2014 #3
    My book ssys the answer is 330Ohm, did I do the calculation wrong?
  5. Nov 5, 2014 #4


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    Staff: Mentor

    The Thévenin resistance is a little over 330Ω so looks like that's the approach they intend.

    Determine the Thévenin resistance of each source, then these are added in series.
    Last edited: Nov 5, 2014
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