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Magnetic levitation
Intermediate
Trains levitated by magnetic force.
Maglev trains use magnets to levitate and propel along a track without contact. Superconductors can levitate above magnets via flux pinning.
Shanghai maglev reaches 430 km/h.
Stable levitation requires special arrangements (Earnshaw).
In more detail
Magnetic levitation uses magnetic forces to balance weight, as in maglev trains and levitating toys. Stable levitation usually requires dynamic or diamagnetic effects, due to Earnshaw's theorem.
Real-world uses
- Maglev trains float above their tracks to reduce friction.
- Diamagnetic levitation demonstrates weak repulsion of materials such as graphite.
- Maglev trains float above their tracks using magnetic forces, which allows fast, smooth travel with little friction.
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Frequently asked questions
Why does a static magnet not levitate stably?
Earnshaw's theorem forbids stable static levitation of magnets alone.
How do maglev trains stay stable?
Electromagnets are controlled dynamically to keep the train in place.
Why do maglev trains not need wheels?
Magnetic forces hold the train above the track, so there is no rolling contact and little friction.
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