Scientists from the Technical University of Denmark (DTU) have confirmed the physics behind the recently discovered magnetic levitation phenomenon. In 2021, a scientist in Turkey published a research article detailing an experiment in which a magnet was attached to a motor, causing the motor to rotate rapidly. When this assembly was brought close to the second magnet, the second magnet began to rotate and suddenly hovered in a fixed position a few centimeters away.

Although magnetic levitation is nothing new (the most famous example is probably Maglev trains, which rely on a strong magnetic force to lift and move) the experiment surprised physicists because the phenomenon was not described by classical physics, or at least not explained by any of them. Known mechanism of magnetic levitation.

But now. Rasmus Björk, a professor at DTU Energy, was intrigued by the Ucar experiment and decided to recreate the experiment together with his graduate student Joachim M. Hermannsen to find out exactly what was happening. Rasmus Björk says that copying is easy and can be done with off-the-shelf components, but the physics behind it are strange:

“Magnets should not sag when close together. They usually attract or repel each other. It turns out that you can make this hanger only if you turn one of the magnets. And this is the weirdest thing. “As you rotate one of the magnets, the force on it should not change, so there seems to be a connection between the movement and the magnetic force,” he says. The results were recently published in the journal Physics Examination Applied.

Various experiments to verify physics

The experiments involved several magnets of different sizes, but the principle remained the same: By spinning the magnet very quickly, the researchers watched as another nearby magnet, called “floating magnets,” began spinning at the same speed and quickly locked in. a position in which it remains suspended.

They found that when the float magnet is locked in place, it is oriented close to the axis of rotation and the similar pole of the rotor magnet. So, for example, the north pole of a floating magnet remained oriented towards the north pole of a permanent magnet when it rotated.

This is different from what would be expected based on the laws of magnetostatics, which describe how a static magnetic system works. However, it turns out that the magnetostatic interaction between rotating magnets is precisely responsible for creating the equilibrium position of the float, as co-author’s graduate student Frederik L. Durhuus discovered using simulations of the phenomenon. They observed that magnet size had a significant impact on levitation dynamics: smaller magnets required a higher rotational speed for levitation because of their greater inertia and ability to float higher.

“It turns out that the floating magnet wants to line up with the rotating magnet but can’t rotate fast enough to do so. And as long as this connection is maintained, it will either remain in the air or remain in the air,” says Rasmus Björk and continues:

“It can be likened to a dzyga. If it’s not spinning, it won’t stand, but by its rotation, it’s locked in position. But when the rotation loses energy, the gravitational force (or in our case, the push and pull of magnets) becomes large enough to overwhelm the balance. Source