BackA rod of length L lies along the y-axis with its center at the origin. The rod has a nonuniform linear charge density , where a is a constant with the units C/m2. Find the electric field strength of the rod at distance x on the x-axis.
An infinite plane of charge with surface charge density 3.2 μC/m2 has a 20-cm-diameter circular hole cut out of it. What is the electric field strength directly over the center of the hole at a distance of 12 cm? Hint: Can you create this charge distribution as a superposition of charge distributions for which you know the electric field?