If a copper wire is wound around a piece of iron, nickel or cobalt, and a voltage is applied to the wire, it takes a longer amount of time for the current to reach its maximum value, than if the iron were replaced with a different material, such as glass— a phenomenon known as inductance. My understanding is within the ferromagnetic substance, the d-orbital electrons come into alignment with the external magnetic field, in a process which substantially increases the flux density of the externally applied field. I was wondering whether it is thought there is any momentum transfer between the d-orbitals and the nucleus causing or facilitating the inductance property? As I side note I was wondering this while playing with the close packing of magnetic spheres with the same # of spheres as common isotope numbers of cobalt, nickel and iron, as well as gadolinium, dysprosium and holmium. Specifically the radial symmetrical geometry for these specific #’s of spheres observed was bipyramid & truncated bipyramid.