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## 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 = Q

_{in}/ [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