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Homework Help: Capacitance per unit length help

  1. Sep 29, 2009 #1
    1. The problem statement, all variables and given/known data[/b]
    You are planning to install a home video studio. A very important piece of information is missing from the specifications. You must find the capacitance per unit length for a coaxial cable. The cable has an inner radius of 1.1 {\rm mm} and an outer conductor 3.1 {\rm mm} in radius separated by polyethylene insulation that acts as a dielectric.

    2. Relevant equations
    (2pi*k*epsilon_0) / (ln(b/a))

    3. The attempt at a solution

    I attempted to use the above formula but do not know what k is, and found on a different website the formula without k so I attempted to use it and got 54.52, which was wrong.

    thanks for any help
  2. jcsd
  3. Sep 29, 2009 #2


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    Gold Member

    Did you look up the dielectric constant of polyethylene? That's what k is.
  4. Sep 30, 2009 #3
    I did not, I'll give it a try. Thank you
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