1. The problem statement, all variables and given/known data There are two slabs on one another. The top slab has current coming out of the page and the bottom slab has current going into the page. y=0 is located between the two slabs. the current density of the top slab is J and the current density of the bottom slab is -J. 2. Relevant equations Is the magnetic field due to the top slab the same as the magnetic field due to the bottom slab? At y=0, what is the magnetic field? 3. The attempt at a solution Finding the magnetic field of one slab with current going one way is easy enough but I am confused the properties of the magnetic field with two slabs on one another. I thought that at y=0, (between the slabs) since there's no current at y=0, the magnetic field would be zero. But I realized that at y=0, this location will experience magnetic field from both the top and the bottom. So what is the amperian loop for this? Will the loop contain both 2 slabs or will the loop be a box inside the two slabs..?