l. (30pts.} A yery long cylindrical wire of radius a. that extends along the zaxis has a current density J: 4w: with 51") J : (1") 31m2 [1 - (rials) where r is the distance to the zaitis. (a) Show that the total current owing through the wire is In. (b) Make a sketch of the cross section of the cylinder on the my showing the direction of the magnetic eld inside and outside of the cylinder. (c) Find the magnitude of the magnetic eld for r