Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Conducting Hollow Tube

  1. Feb 11, 2007 #1
    1. The problem statement, all variables and given/known data
    A very long conducting tube (hollow cylinder) has inner radius a and outer radius b. It carries charge per unit length +alpha , where alpha is a positive constant with units of C/m. A line of charge lies along the axis of the tube. The line of charge has charge per unit length +alpha .

    What is the charge per unit length on the inner surface of the tube?

    What is the charge per unit length on the outer surface of the tube?

    I've found the electric field where r < a, a < r < b, r > b already but I'm not sure how to apply that to the follow questions.
  2. jcsd
  3. Feb 11, 2007 #2


    User Avatar
    Science Advisor

    Is there a "discontinuity" in the electric field at r= a? (Is the value using the formula for r< a, but taking r= a, different from the value for r> a?) If so, there must be a charge there to account for the difference.
  4. Feb 11, 2007 #3
    I'm confused on what you said, the difference is going to be the charge per length for partA/B ?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook