Levitation (physics)
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Levitation (from Latin levitas, lit. 'lightness')[1] is the process by which an object is held aloft in a stable position, without mechanical support via any physical contact.
Levitation is accomplished by providing an upward
Physics
Levitation (on
Levitation techniques are useful tools in physics research. For example, levitation methods are useful for high-temperature melt property studies because they eliminate the problem of reaction with containers and allow deep undercooling of melts. The containerless conditions may be obtained by opposing gravity with a levitation force instead of allowing an entire experiment to freefall.[2]
Magnetic levitation
Magnetic levitation is the most commonly seen and used form of levitation. This form of levitation occurs when an object is suspended using magnetic fields.
It is possible to levitate pyrolytic graphite by placing thin squares of it above four cube magnets with the north poles forming one diagonal and south poles forming the other diagonal.[3] Researchers have even successfully levitated (non-magnetic) liquid droplets surrounded by paramagnetic fluids.[4] The process of such inverse magnetic levitation is usually referred to as Magneto-Archimedes effect.
Magnetic levitation is in development for use for transportation systems. For example, the Maglev includes trains that are levitated by a large number of magnets. Due to the lack of friction on the guide rails, they are faster, quieter, and smoother than wheeled mass transit systems.
Electrodynamic suspension uses AC magnetic fields.
Electrostatic levitation
In electrostatic levitation an electric field is used to counteract gravitational force. Some spiders shoot silk into the air to ride Earth's electric field.
Aerodynamic levitation
In aerodynamic levitation, the levitation is achieved by floating the object on a stream of gas, either produced by the object or acting on the object. For example, a
Gas film levitation
This technique enables the levitation of an object against
Acoustic levitation
Acoustic levitation uses sound waves to provide a levitating force.
Optical levitation
Optical levitation is a technique in which a material is levitated against the downward force of gravity by an upward force stemming from photon momentum transfer (radiation pressure).
Buoyant levitation
Gases at high pressure can have a density exceeding that of some solids. Thus they can be used to levitate solid objects through buoyancy.[5] Noble gases are preferred for their non-reactivity. Xenon is the densest non-radioactive noble gas, at 5.894g/L. Xenon has been used to levitate polyethylene, at a pressure of 154atm.
Casimir force
Scientists have discovered a way of levitating ultra small objects by manipulating the
Uses
Maglev trains
Magnetic levitation is used to suspend trains without touching the track. This permits very high speeds, and greatly reduces the maintenance requirements for tracks and vehicles, as little wear occurs. This also means there is no friction, so the only force acting against it is air resistance.
Animal levitation
Scientists have levitated frogs,
Further reading
- Charles P. Strehlow; M. C. Sullivan (2008). "A Classroom Demonstration of Levitation...". American Journal of Physics. 77 (9): 847–851. S2CID 119108808..
See also
- Levitation (illusion)
- Levitation based inertial sensing
- Anti-gravity
- Flight
- Leidenfrost effect
- Telekinesis
- Weightlessness
References
- ^ Levitate, "to rise by virtue of lightness," from Latin levitas "lightness," patterned in English on gravitate: Online Etymology Dictionary
- ^
- S2CID 53607312
- ^ http://www.mrs.org/s_mrs/sec_subscribe.asp?CID=12048&DID=275340&action=detail Materials Processing Through Levitation in High Gas Pressure
- ^ "Scientists reveal secret of levitation, Yahoo! News". yahoo.com.
- ^ "Levitation in Miniature, Null Hypothesis". null-hypothesis.co.uk. Archived from the original on 2011-07-17. Retrieved 2007-08-23.
- ^ "Frogs Levitate in a strong enough magnetic field". physics.org. Retrieved 20 November 2014.
- ^ "NASA Levitates a Mouse With Magnetic Fields". Popular Science. September 9, 2009. Retrieved 20 November 2014.
- ^ [1] Mice Levitated in Lab
External links
- The dictionary definition of levitation (physics) at Wiktionary
- Diamagnetic Levitation (YouTube)
- Superconducting Levitation Demos