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Resistors and Ohmmeter

  1. Feb 24, 2007 #1
    1. The problem statement, all variables and given/known data

    For the resistor network shown in the figure, the ohmmeter reads 20.2 ohm.


    What is the resistance of the resistor X?

    2. Relevant equations

    See below.

    3. The attempt at a solution

    I’m uncertain if I tackled the system correctly, so please guide me on any misconceptions in my workings.

    For an ohmmeter, I didn’t come across any special formulas like for a voltmeter, and I may have not addressed any typical properties for ohmmeter readings . . .

    Are the 75.0 ohm and 55.0 ohm in series? And then X; R_75+55; R_115, and R_85 will be in parallel?

    (1/R_eq) = (1/R_x) +(1/115.0 ohm) +(1/130.0 ohm) + (1/85 ohm)
    (1/R_x) = (1/20.2 ohm) – (1/115.0 ohm) –(1/130 ohm) – (1/85 ohm)
    = 0.02135 1/ohm

    R_x = 1/0.0214 1/ohm = 46.8 ohm ???

  2. jcsd
  3. Feb 24, 2007 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Looks good to me!
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