Hi, Quick description of the problem at hand: spherical perfect conductor around the origin with radius a, spherical shell (with radius b) around it made of a material with given magnetic permeability bigger than 1. Uniform Magnetic field in the area. The solution I am looking at (which I won't post as it isn't in english) uses the fact that the surface current on r=b, that is on the surface of the shell with permeability bigger than 1, is zero, as one of the boundary conditions for the solution. My question is why can we assume this ? why can there be no surface current on a material such as this ? Can we conclude definitively that it is not a perfect conductor ? if so we can say it either has finite conductivity or no conductivity, in both cases there can't be any surface current, but I couldn't justify the claim that this material is definitely not a perfect conductor. Am I even thinking in the right direction ? thanks !