Athick spherical shell (centered at the origin, inner radius r, outer radius 2r) carries a volume charge distribution p(r) = k/r, where k is a negative constant. a. use coulomb's law to write an integral expression for the electric field at an arbitrary point on the x-axis (x, 0, 0). b. use gauss's law to find expressions for the electric field in all regions of space. c. graph the x-component of the electric field as a function of position along the x- axis.