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Homework Help: Resistances in Series or Parallel

  1. Jul 1, 2009 #1
    1. The problem statement, all variables and given/known data
    You are given three identical resistors, each of 100 Ohms. Show how by using them singly or in series, parallel or series-parallel combinations you can obtain a resistance of 66.7.

    2. Relevant equations

    3. The attempt at a solution
    The only way I could think of arranging the resistors in order to obtain a resistance of 66.7 Ohms was if 2 resistors connected in series were parallel to 1 resistor. Is this even possible? Or is there another solution?
  2. jcsd
  3. Jul 1, 2009 #2
    Why not? It is correct.
  4. Jul 1, 2009 #3


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    Homework Helper

    Well what does it work out to?

    The equivalent is a 200 || 100, so that looks like it's right. All 3 || would yield 33 ohms, so ... must only be the one solution.
  5. Jul 1, 2009 #4


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    Science Advisor

    Of course it's possible (and correct, as noted). See the attached image.

    Attached Files:

  6. Jul 1, 2009 #5
    Well it was the only solution I could think of but I wasn't sure if I could parallel them that way. If I can then I think it's safe to assume it's correct.
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