# Resistance Between Terminals AC and AD

1. Feb 12, 2010

### shimizua

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. Feb 12, 2010

### kuruman

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?

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook