A long cylinder of charge q has a radius a. The charge density within its volume, s, is uniform (Fig. 11.11). Describe the form of the electric field generated by the cylinder. Find the electric field strength at a distance r from the axis of the cylinder in the regions (i) r > a and (ii) 0 < r < a. If a non-relativistic electron moves in a circle at a constant distance R from the axis of the cylinder, where R > a, find an expression for its speed.