1. The problem statement, all variables and given/known data A thick slab extending from z=-a to z=+a carries a uniform volume current J=J (in the x direction) Find the magnetic field, as a function of z, both inside and outside the slab. 2. Relevant equations ∫Bdl=(µ0)Ienc 3. The attempt at a solution I am not sure how to start this. Could someone explain why B is a function of z? Is this just a set-up for the question, or is B obviously a function of z? I also don't really know how to conceptually explain this problem. Thanks!