How to Control Engaging and Disengaging Magnetism in Electromagnetic Devices?

Technically you can magnetize two things to, "stick," together then apply another field that would cause them to fly apart. The field would be orthogonal to the pre-existing field.

As for a relatively thin piece of glass with a ferrous film attached, I don't know how practical that would be in terms of magnetic field strength and sticking together with a good deal of force. Glass is quite difficult to separate if there is a viscous film between them owning to air pressure. The force in the magnet is directly proportional to how many domains are aligned in the same direction, film doesn't have that many say relative to an audio speaker magnet.

Who know, it could be worked out, sounds like an Apple idea.

kj

This maybe be a ridiculous thought, but I'm sharing it in case it has any merit: Perhaps you could use permanent magnets and what if one of the magnets were heated to it's Curie point such that it loses it's magnetic force. When the magnet cools below it's Curie point it's magnetism would return. Perhaps this could be done by passing a current though the magnetic strip to heat it up. The magnet would, of course, need to be able to conduct electricity.

But, the magnet would have to get pretty hot and I suppose this might break the glass, unless it's some kind of tempered glass, or there is some kind of thermal insulation between the glass and the magnet, or if it happened fast enough.

Anyway, just a thought.

Another thought, again with permanent magnets: How about if one of the magnets has a winding around it such that when current is applied it opposes the magnetic field from the permanent magnet. The electromagnet component would generate a field strong enough to either weaken the existing field enough for gravity to take over, or even to completely cancel the field or reverse it.

What would be fun is finding another way to do what an electromagnet does. And I think Mr. Lawson is touching on such thoughts. Why reinvent the wheel, lets fly!

what about aluminium with controlled frequency ??
Paramagnetism