I first heard about magnetic viscosity (V[s])a few weeks ago. As I understand it, there's a time delay in ferromagnetic materials between an applied H field and the corresponding B field (and in reverse also -- removing the H field).
If I spin a magnet over a ferromagnetic disc (assume non-conductive), I would think that without magnetic viscosity, it would just be attracted to the magnet as if it weren't spinning. With viscosity, I'd expect an angular difference between the magnet's flux lines and the induced flux in the disc. As the speed increases, it seems the phase angle would exceed 90 degrees and the disc would be repelled. Has that been observed? What materials have the highest V[s]? Thanks, Hoyt Stearns Scottsdale, Arizona US
