(a) Sketch the electric field lines for an infinite line of charge. You may find it helpful to show the field lines in a plane containing the line of charge in one sketch and the field lines in a plane perpendicular to the line of charge in a second sketch.
(b) Explain how your sketches show (i) that the magnitude E of the electric field depends only on the distance r from the line of charge and (ii) that E decreases like 1/r.