hey sorry for the prolific posting but exam's are coming up and i'm just working through past papers. two conducting parallel plates have uniform uniform current densities flowing through them parallel to their surface. Use Ampere's Law to find the magnetic field inside and outside the plates. im quite confused as to where to take my loops here in order to find the field at all the various places im reuqired to. any suggestions? also why does the following argument not work here: integrate round an amperian loop that doesn't intersect either plate and get B(r)-B(r+dr)=0 as no enclosed current gives B(r)=B(r+dr) implies B(r)=0 but B goes to 0 at infinity so B is zero outised the plates???