Electric field varies with r

  • #1

Homework Statement


based on the diagram attached, find the electric field E that varies with r.
the line and the metallic cylindrical shell are infinitely long.
the outer radius of the cylindrical shell is b and the inner one is a
and the line charge density for the line is [tex]\lambda[/tex]
and the line charge density for the cylindrical shell is [tex]\lambda[/tex]s

Homework Equations


Gauss's Law ( [tex]\oint[/tex]E dA = Qin / [tex]\epsilon[/tex]


The Attempt at a Solution


by using gauss's law with cylindrical gaussian surface coaxial with the line,
when r < a, i have E = [tex]\lambda[/tex] / (2*pi*[tex]\epsilon[/tex]*r);
for a< r < b, i have E = 0 since the shell is a conductor;

but for r > b, is it E = ([tex]\lambda[/tex]s + [tex]\lambda[/tex]) / (2*pi*[tex]\epsilon[/tex]*r) since the total charge enclosed is the sum of charges in the two bodies?

Pls help me. thanks
 

Attachments

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Answers and Replies

  • #2
vela
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Your calculations are correct.
 

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