Why does a solenoid coil move when a large current is sent through it?

[Salamon]

If you were to place something like a 100 turn coil of wire around an iron rod and position it toward the end of the rod, why does the coil quickly move to the center of the rod when a large current is sent through it?

I understand that a magnetic field is produced by the current which resembles the magnetic field of a bar magnet. I understand that the iron has now become magnetized. I don't understand why the wire must move downward as a result though.

 

[cragar]

Might have something to do with lenz's law. When you plug it in we get a change in current and this creates a changing B field which induces an E field and this E field cause charge to flow in the iron and creates another B field, And this will oppose the change in B flux.

 

[shoestring]

I think it is because dipoles often move toward stronger field. Well, for diamagnets it's the opposite effect, because the induced magnetic moment opposes the field (that's why frogs have been kept floating in mid-air above a strong magnet), but iron will be magnetized with the field and hence move toward stronger field. Parallel currents attract, so the current in the coil and the atomic currents in the iron will affect each other, moving them closer.

Edit: There's a similar effect in the fringe field of a parallel plate capacitor.