A circular beam of charge of radius a consists of electrons moving with a constant speed u along the + z direction. The beam’s axis is coincident with the z-axis and the electron charge density is given by v = - cr2 (c/m3) where c is a constant and r is the radial distance from the axis of the beam.
(a) Determine the charge density per unit length.
(b) Determine the current crossing the z-plane.