Hi While studying the shielded wires, i noticed that the magnetic field of the inner conductor can penetrate the shield conductor (can be calculated in the region 3). However, the boundary condition of the magnetic field at the surface (between dielectric and perfect conductor) of a perfect conductor impose that the tangential component of H (Ht = Js surface current density) and the normal component is Hn = 0. Inside the perfect conductor, we have Ht = 0 and Hn = 0. So why do we superpose the magnetic field of the inner conductor and the outside conductor when calculating the magnetic field in the region 3 ? Why we still have Hi (inner cond) in the region 3 ?