- Levitation
Levitation (from
Latin "levitas" "lightness") ["Levitate", "to rise by virtue of lightness," from Latin "levitas" "lightness," patterned in English on "gravitate": [http://dictionary.reference.com/search?q=levitate Online Etymology Dictionary] ] is the process by which an object is suspended againstgravity , in a stable position, without physical contact.It is also a
conjuring trick, appearingly raising a human being (or other object) without any physical aid. The illusion can be produced by clevermechanics , lighting arrangements and other means.Physics
For levitation on
Earth , first, a force is required directed vertically upwards and equal to the gravitational force, second, for any small displacement of the levitating object, a returning force should appear to stabilize it. The stable levitation can be naturally achieved by, for example magnetic or aerodynamic forces. With the former, it is essential that diamagnetic elements are used. In this case the returning force appears from the interaction with thescreening currents . For example, a superconducting sample, which can be considered either as a perfect diamagnet or anideally hard superconductor , easily levitates an ambient external magnetic field. In very strong magnetic field, by means ofdiamagnetic levitation even small live animals have been levitated.By means of aerodynamic forces, the effect of levitation can also be achieved using the upthrust of air, with the levitating object having the same average density as air.
Scientists have discovered a way of levitating ultra small objects by manipulating the so-called
Casimir force , which normally causes objects to stick together byquantum force . This practice however, is only possible for micro-objects. [ [http://news.yahoo.com/s/afp/20070806/sc_afp/britainsciencelevitation_070806132733 Scientists reveal secret of levitation, Yahoo! News] ] [ [http://www.null-hypothesis.co.uk/science/news/item/levitation_magic_nanotechnology_particles_research Levitation in Miniature, Null Hypothesis] ]Further reading
* esp. the section on levitation in the chapter on
electromagnetism .
*.References
See also
*Types of physical levitation:
**Acoustic levitation
**Aerodynamic levitation
**Electrostatic levitation
**Magnetic levitation
**Optical levitation
*Anti-gravity
*Flying Saints
*Illusion s
*Laputa
*Balducci levitation
*Sooperman
*King levitation
*Party Levitation
*Metaphysical levitation
*Weightlessness
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