Poynting effect: Difference between revisions
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The '''Poynting effect''' may refer to two unrelated physical phenomena. Neither should be confused with the [[Poynting–Robertson effect]]. All of these effects are named after [[John Henry Poynting]], an English physicist. |
The '''Poynting effect''' may refer to two unrelated physical phenomena. Neither should be confused with the [[Poynting–Robertson effect]]. All of these effects are named after [[John Henry Poynting]], an English physicist. |
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Revision as of 05:50, 22 July 2009
The Poynting effect may refer to two unrelated physical phenomena. Neither should be confused with the Poynting–Robertson effect. All of these effects are named after John Henry Poynting, an English physicist.
Chemistry
The ability to combine nitrous oxide and oxygen at high pressure while remaining in the gaseous form is due to the Poynting effect.
Entonox is a 50:50 combination of the anesthetic gas nitrous oxide and oxygen. This combination is useful because it can provide a sufficient concentration of nitrous oxide to provide analgesia (pain relief) in sufficient oxygen so that the risk of hypoxemia is eliminated. This makes it safe to use by para-medical staff such as ambulance officers. However the ability to combine these two gases at the temperature and pressure in the cylinder while remaining in the gaseous form is unexpected based on the known properties of the two gases.
The Poynting effect involves the dissolution of gaseous O2 when bubbled through liquid N2O, with vaporisation of the liquid to form a gaseous O2/N2O mixture.
Materials science
In materials science the Poynting effect, refers to the creation of (deviatoric) normal stresses or strains in response to an imposed shear stress at large strains [1][2].
References
- ^ HAN-CHIN WU; Continuum Mechanics and Plasticity in: David Gao and Ray W. Ogden (Eds.); Modern Mechanics and Mathematics; Chapman & Hall / CRC, Boca Raton, U.S.A.; 2005; p. 189
- ^ [http://www.nat.vu.nl/~fcm/Papers/NatMatSub2.pdf Negative normal stress in semiflexible biopolymer gels by Paul A. Janmey, Margaret E. McCormick, Sebastian Rammensee, Jennifer L. Leight, Penelope C. Georges and Fred C. MacKintosh]