Magnetic vector potential of current segment. A very long (but not infinite) straight wire carries a current I and is located in free space.
(a) Calculate the magnetic vector potential at a distance Q from the center of the wire. Assume for simplicity that the wire extends from -L to +L and that L > > Q.
(b) From the result in (a), what must be the magnetic vector potential for an infinitely long current-carrying wire?