The animation shows two co-axial wire loops carrying
current in the same sense (represented by the spheres) which are connected by a spring (not shown).
As the current is slowly ramped up, the magnetic force between the rings causes them to attract one another.
Then, as the current ramps down again, the restoring force of the spring returns them to their original separation distance.
We show the field configuration here using the "iron
filings" representation. The bottom wire loop carries
three times the current of the top wire loop.