Hi. This thred will sort of be "my thread" i suspect for various concepts I still do not get after two semesters of college physics (my final is in two days). Without further ado, I'll ask my first question: Here's how the problem reads: A long nonconducting cylinder (radius = 12 cm) has a charge of uniform density (5.0 nC/m^3) distributed throughout its column. Determine the magnitude of the electric field 5.0 cm from the axis of the cylinder. If they said to determinte it at a radius larger than the radius of the cylinder itself, I would most likely have no problem solvingit; but how do I solve it when they ask for the electric field 5 cm from the axis (i.e., r<R)?