Magnetic Levitation

As a kid, you've probably tried to push two magnets together with the same poles facing, and felt them shove back. That invisible pushing force between magnets is called repulsion.

Maglev trains use exactly this principle. Powerful electromagnets are placed on the bottom of the train and along both sides of the track, with the same poles facing each other. The train then floats up in the air above the track. There's also a method that works the other way around. It uses the pulling force between magnets (attraction) to lift the train from below, almost like hugging the rail.

When nothing touches the ground, the friction with the track disappears completely. The rattling noise and vibration of wheels rolling over rails go away, and there are no parts to wear out. With no rolling friction loss, the train glides smoothly. Still, the faster it goes, the more air resistance grows, and it takes a lot of power to overcome that.

If you simply set an object on top of a magnet, it easily loses its balance and slides off to the side. It's like trying to float a magnet over a desk. It quickly flips over or shoots away.

That's why a train lifted by attraction doesn't stop at just floating. It also uses real-time electronic control so it never drifts off the center of the track. Sensors constantly measure the gap to the rail. A computer adjusts the strength of the current in tiny steps over very short intervals, tightly correcting the train's position so it always floats right in the middle of the rail.

The force that pushes the train forward is also made by magnets. The magnetic poles around the track switch back and forth between north and south. This way, the magnets pull the train from the front and push it from behind, creating strong forward thrust. Lifting, staying centered, and moving ahead are all done by the power of magnets.

To be a bit more precise, floating a train nearly 10 centimeters high and running it at very high speed takes extremely strong magnets. If you push too much current through an ordinary electromagnet, the coil can't take the enormous heat.

The key technology used here is superconductivity, a phenomenon where electrical resistance vanishes completely. A superconducting coil can carry a huge current continuously without producing heat. That makes it a far more powerful electromagnet than an ordinary one.

When the superconducting magnets on the train zip past the coils in the track, electromagnetic induction creates current and magnetic fields in the track coils as well. These magnetic fields push and pull on each other. They lift the train 10 centimeters into the air. Whenever the train sways left or right, they also create a magnetic restoring force that pushes it back toward the center, so it runs stably.