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Homework Help: 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.

    yf_Figure_26_491.jpg

    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 ???

    Thanks.
     
  2. jcsd
  3. Feb 24, 2007 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Looks good to me!
     
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