A long electron beam has a volume charge density of pv = pv0*e^p for p< a , where is the cylindrical radial coordinate. The charge density (i.e., the electrons) is traveling in the z direction with a velocity u = 0.2 c, where c = 3 x 108 m/s is the speed of light. (a) Find the current density any distance p from the axis, and b) Find the total current flowing in the z direction