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Electric field in a hollow cylinder

  • Thread starter magnifik
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  • #1
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An infinitely long thick hollow cylinder has inner radius Rin and outer radius Rout. It has a non-uniform volume charge density, ρ(r) = ρ0r/Rout where r is the distance from the cylinder axis. What is the electric field magnitude as a function of r, for Rin < r < Rout?

for this problem, when you find qinside, do you integrate from Rin to r or from Rin to Rout? i'm confused because i would have expected it to be the latter, but in the solutions they integrate from Rin to r. can someone please explain this?

also, if you try to find the e-field where r > Rout, do you integrate from r to Rout?

Solution is here (problem II):
http://www.physics.gatech.edu/~em92/Classes/Fall2011/2212GHJ/main/quiz_help/200908/q2s.pdf
 
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Answers and Replies

  • #2
rude man
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Just use Gauss' theorem. The surface has radius r, and
q(inside) is whatever's inside!
 
  • #3
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Just use Gauss' theorem. The surface has radius r, and
q(inside) is whatever's inside!
since in the example in the document it asks for Rin < r < Rout.. why does it integrate from Rout to r??
 
  • #4
rude man
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It doesn't. It integrates from Rin to r.
 
  • #5
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It doesn't. It integrates from Rin to r.
but why not Rin to Rout?
 
  • #6
rude man
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Because ity asks for the field at Rin < r < Rout, not AT Rout.
 

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