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Homework Help: Cylindrical Capacitors Questions

  1. Mar 8, 2010 #1
    1. The problem statement, all variables and given/known data
    An isolated cylindrical capacitor consists of two concentric conducting cylinders of length L and radii a and b. The inner and outer conductors carry +Q and -Q, respectively.
    a. Determine the electric field between the conductors.
    b. Determine the electric potential difference between the two conductors.
    c. What is the capacitance of this device?

    2. Relevant equations
    V=[tex]\int[/tex]E dL
    [tex]\oint[/tex]E dA=Q/Epsilon

    3. The attempt at a solution
    a. I got as my answer E=Q/(2[tex]\pi[/tex]Epsilon not (aL))
    b. I used the integral with V and got Q/(2[tex]\pi[/tex]Epsilon not (a) (ln(b/a))
    c. I plugged my answer from b into C=Q/V and got ln(b/a)/(2[tex]\pi[/tex]Epsilon not (a))

    I am not sure if I did any of these right...
  2. jcsd
  3. Mar 8, 2010 #2


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    Homework Helper

    Is the electric field independent of position?

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