An infinite wire oriented in the z direction has a cross-sectional current density J. In other words, I= J. dA. For this problem, take = [(21)/(a)] (1 (r/a)) for r a, where a is the radius of the wire, r is the radial distance from the wire axis, and Io is the total current. Use Ampere to figure out the following... a) The total current passing through the entire cross-section of the wire. b) The magnitude of the magnetic field B outside of the wire at some radius r > a? c) The current I contained in a circular cross-section of radius r