Electric potential along the axis of a cylindric tube

[Physics_101]

Homework Statement

Imagine a cylinder of radius R and Length L. Both of it's ends are open and it carries a uniform surface charge desnity of sigma (@) Find the electric potential at any point along the axis of the cylinder, and then use that to calculate the electric field at any point.

Homework Equations

The Attempt at a Solution

Essentially the way you are supposed to do this problem (I think) is to assume the tube is just a bunch of stacked line charges (rings), and then find the potential from a ring, and then integrate from 0 to L or something, I'm having real trouble doing so however, any help out there?
Thanks

 

[chrisk]

Your concept is correct. Find dE for a ring line of charge and keep in mind dE has only an axial component due to symmetry. Try setting up the intergral and post it.