Lenz's Rule and Ferromagnetism

[TP9109]

Hi,
In this video: , it shows someone with an aluminium ring next to an MRI scanner. He allows the ring to fall over and it falls slowly demonstrating Lenz's law. I understand this but was wondering what would happen if a ferromagnetic ring was used instead of the non-ferromagnetic aluminium ring used in the video.
Obviously I know it would be dangerous and would be attracted to the scanner, but with regards to Lenz's law, in my mind as it accelerates quickly towards the scanner, it would undergo changes in magnetic field so wouldn't a powerful induced magnetic field be induced in the ring (Lenz's law) as it is flying towards the scanner that acts in the opposite direction to the scanner's field?
In other words I am basically asking whether Lenz's law works exactly the same with a ferromagnetic ring as it does with the non-ferromagnetic ring in the video. Because if it does then would you not

 

[Dale]

Summary:: Lenz's law with a ferromagnetic object.

In other words I am basically asking whether Lenz's law works exactly the same with a ferromagnetic ring as it does with the non-ferromagnetic ring in the video.

Lenz’s law does work with a ferromagnetic object.

The key principle demonstrated in this video is actually eddy currents being formed through Faraday's law and Ohm's law. Lenz's law is just the minus sign in Faraday's law, which is what makes it so that the eddy currents work to slow the motion rather than to accelerate it.

For ferromagnetic objects the conductivity is lower so eddy currents are smaller. Also, ferromagnetic objects are usually not a good shape for forming large eddy currents. So the result is that ferromagnetic objects often become projectiles instead of moving slowly.