8. A uniformly charged disk has a radius R = 0.5 m and carries a total charge Q = 16x10'5 C. a. What is the surface charge density on the disk? b. What is the magnitude and direction of the electric eld at point P which lies on the x-axis at a distance x = 0.4 m from the disk? c. On the axes below, graph the electric eld as a function of distance x. E X d. If instead of the disk you have an infinite sheet of charge with the same surface charge density, is the electric field at point P the same, less, or greater that the electric field of the disk? Justify your