1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
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: Electric Potential within coaxial cylinder

  1. Feb 20, 2008 #1
    1. The problem statement, all variables and given/known data
    A long metal cylinder with radius a is supported on an insulating stand on the axis of a long, hollow metal tube with radius b. Thew positive charge per unit length on the inner cylinder is [tex]\lambda[/tex], and there is an equal negative charge per unit length on the outer cylinder. Calculate the potential for r < a; a < r < b; r > b.

    2. Relevant equations
    Va - Vb = [tex]\int[/tex]E.dl

    3. The attempt at a solution
    I really just need help figuring out why the answer for when r < a is:
    The reference point here is b. If we are looking for the potential INSIDE the smaller cylinder with radius a, then why are we only integrating from b to a? Shouldn't it be from b to 0? Or is the potential inside the smaller cylinder constant? Why would that be?
    Last edited: Feb 20, 2008
  2. jcsd
  3. Feb 20, 2008 #2
    Well what IS the potential inside a hollow conductor at equilibrium? The electric field is zero, right? so...
  4. Feb 20, 2008 #3
    The smaller cylinder is not hollow and I don't think its a conductor (and its supported on an insulating stand anyway)... unless being "metal" is synonymous with conductor? E inside a conductor is 0, but I don't think the smaller cylinder is a conductor.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook