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Resistance Between Terminals AC and AD

  1. Feb 12, 2010 #1
    1. The problem statement, all variables and given/known data
    What is the resistance between terminals AC? What is the resistance between AD?

    An underground telephone cable, consisting of a pair of wires, has suffered a short
    somewhere along its length (at point P in the Figure). The telephone cable is L long,
    and to determine where the short is, a technician first measures the resistance between
    terminals AB to be RAB; then he measures the resistance across the terminals CD to be
    RCD.

    http://capa-new.colorado.edu/teacher/capalibrary/Graphics/Gtype58/prob08.gif



    2. Relevant equations
    So I know that to find resistance we do R=pl/A but I dont really know how I would find it in this situation since it is not like finding AB or CD like I have done before. Please help



    3. The attempt at a solution
    Not sure if I would just kinda do something like
    R(ac)=pL/A ? and just have it be that simple and then
    R(ad)=pL/A + R(cd) ? please help
     
  2. jcsd
  3. Feb 12, 2010 #2

    kuruman

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    Homework Helper
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    Say x is the distance from A to the short. Can you write an expression for the resistance RAB in terms of x? How about an expression for RCD in terms of x?
     
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