Moving Iron question

As I understand it, the motion of a magnet relative to a fixed coil will induce a varying current in that coil. Similarly the motion of a coil relative to a fixed magnet will induce a varying current in the coil. How does a Moving Iron Cart like the Grado or Soundsmith induce a current when the moving element is neither a coil nor a magnet. Any help here?

Thanks in advance,


Thanks for the link, but the Grado explanation is that the moving iron element creates an increase in one flux gap and a decrease in another as it moves back and forth on the cantilever. I don't quite understand what that means or how it induces a current. If there were already a constant current, I think I understand how it could impede that as it moves, but I don't understand how it could induce current.

'Induction' means that a field from a magnet is used to strengthen the smaller field of a magnetic material attached to the cantilever by means of proximity. The smaller material can be iron oxide.

This increases the field strength and keeps the moving mass low.