A few of my classmates and I are in a debate about whether or not there would be a magnetic field within a hollow cylinder. The problem has a solid cylinder with current running (throughout the solid) along its axis. Slightly off-center is a hollowed out 'hole' that runs the length of the infinite cylinder. We are arguing over whether or not there is a B-field in there, one side says no and the others are saying yes. We've shown each other our mathematical arguments but the debate proceeds. Can anyone confirm either in the affirmative or negative? One side is using the argument of vector potential being present, and the other is using an Amperian loop to show it is zero as no current is enclosed.