Magnetic levitation,

 Maglev, or magnetic suspension is a method by which an object is suspended with no support other than magnetic fields. Magnetic force is used to counteract the effects of the gravitational acceleration and any other accelerations.

The two primary issues involved in magnetic levitation are lifting forces: providing an upward force sufficient to counteract gravity, and stability: ensuring that the system does not spontaneously slide or flip into a configuration where the lift is neutralized.

Magnetic levitation is used for maglev trains, contactless melting, magnetic bearings and for product display purposes.

Advantages

• Magnetic levitation trains in Germany and Japan are capable of reaching speeds up to 500 kmh^–1. They are faster than conventional train systems.
• Maglev systems do not use steel wheels on steel rails. Because magnetic levitation trains do not touch the guide way the high cost of maintaining precise alignment of the tracks to avoid excessive vibration and rail deterioration at high speeds is not a problem.
• Maglevs can provide sustained speeds greater than 500 kmh^–1 limited only by the cost of power to overcome wind resistance.
• Maglevs do not touch the guide way. This confers advantages such as: faster acceleration and braking, greater climbing capability; enhanced operation in heavy rain, snow and ice.
• Maglev transportation offers an alternative to mass transit problems in major metropolitan areas where traffic on ground and air has become too congested.
• Maglev systems are energy efficient. For long distance travel they use about half the energy per passenger as a typical commercial aircraft.

Cite: https://en.wikipedia.org/wiki/Magnetic_levitation

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