Electric Field due to Solid Non-Conducting Cylinder

[thiefjack]

Homework Statement

Positive charge is distributed throughout a solid non-conducting cylinder of radius 'b ' and infinite length. The charge density increases with radius according to ρ = ${ρ}_{o}$(${r}{^2}/{b}{^2}$), where ${ρ}_{o}$ is a constant (evidently equal to the charge density at the surface of the cylinder).

Find the electric field intensity, E, as a function of radius, outside the cylinder.

Homework Equations

E = k${dq}/{r}^{2}$

The Attempt at a Solution

Not sure where to get started, actually. If we try to find the electric field intensity at a position outside the cylinder wouldn't it be dependent on how far out we're finding the electric field and not dependent on the radius?

 

[Spinnor]

This is a straight forward application of Gauss's Law. See example 1.4 which is similar to your problem.

http://ecee.colorado.edu/~bart/book/book/chapter1/ch1_3.htm

See also,

http://www.chem.ox.ac.uk/teaching/Physics%20for%20CHemists/Electricity/Gauss.html

http://research.physics.illinois.edu/PER/unit4.pdf

 

[thiefjack]

I got the right answer with your help, Spinnor.

Thanks for the pointing me in the right direction.