Hi, i'm new here, and i'm sure you will be hearing from me often in here anyway, my question is in regards to finding the potential of a cyllinder, with uniform volume charge sigma, radius r, and length L. In this case, I need to find the potential along the axis of the cylinder, but outside of the charge distribution. I have an idea how to do it, let me know if i'm on the right track. I decided the best way to go about doing this is to find the electric field resulting on the point of reference from a disk of charge, with surface charge d(sigma), and building the cylinder out of an infinite amount of disks from distance z to distance z+L- then using the electric field to find the electric potential. I found the electric field resulting from the disk of charge, but am having trouble setting up the integration to find the field due to the volume, because theta varies, and so does the distance from the disk and the point of reference. Any help would be appreciated. Does anyone know of an easier way to tackle this problem? here's a picture of the problem to make things easier: http://i43.photobucket.com/albums/e394/risendemonx/potentialcylinder.jpg oh, and one last thing: since i'm new here, can anyone show me how to post equations and pictures directly to the thread? thanks a bunch!