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Homework Help: Griffiths 4.21

  1. Oct 11, 2015 #1
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
    I understand all the calculations here - http://www.physicspages.com/2012/10/18/coaxial-cable-with-dielectric/
    I have one issue that is bugging me though - if λ charge density is distributed over the inner conductor, why can it be assumed that the same -λ is distributed over the outer shell? Aren't there any bound charge densities involved here?

    Thank you.
  2. jcsd
  3. Oct 11, 2015 #2


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    With bound charge densities you mean the polarization ? That is involved. That's why (for ##\epsilon_r > 1##) C is greater than for the same coax without the dielectric. But the ##\lambda## are the same: polarization has no total charge.
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