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Homework Help: Calculate the capacitance per unit length of the cable

  1. Feb 14, 2010 #1
    1. The problem statement, all variables and given/known data
    The coaxial cable from a television or other device has an inner conductor with diameter of 1 mm and the shield of diameter 5 mm. Assume a plausible value for the dielectric constant (3 ≤ κ ≤ 5) of the dielectric separating the two conductors and calculate the capacitance per unit length of the cable.

    2. Relevant equations

    3. The attempt at a solution
    I am really unsure of how to even start this problem. The answer they are looking for is a range ____ nF/m <= C/L <= _____ nF/m. Thanks in advance!
  2. jcsd
  3. Feb 14, 2010 #2


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    Homework Helper

    Start by assuming that one unit length of the cable has a charge Q. What would be the potential difference across the shield?
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