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Science - Science (general) | | French term or phrase: La force de pression de radiation | From a museum presentation on the Doppler effect:
L'atome n'absorbe que les photons ayant une fréquence très précise. Pour un choix judicieux de la fréquence des lasers, l'effet Doppler favorise l'absorption par l'atome des photons opposés à sa course. La force de pression de radiation qui en résulte est alors opposée au
mouvement de l'atome, et les atomes sont donc freinés.
Thanks for any insights! |
| | | English translation:force due to radiation pressure | Explanation:
As it says. Electromagnetic radiation does indeed exert a pressure, often enough to push a spacecraft off course.
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Note added at 6 hrs (2008-10-15 17:49:01 GMT)
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Diane: Force and pressure are NOT the same thing. Pressure is a force per unit area, and can therefore be very small if the area is very large, and vice versa. The pressure exerted at the tip of a needle can be (and often is) large enough to exceed the fracture strength of many materials, in other words, it makes an indentation or scratch. This will only happen at a stress (which is also pressure) of several MPa, even though the FORCE may only be a few newtons (1kgf = 10N approx).
Sorry to go on about this, but the distinction is important: the FORCE is a consequence of the radiation PRESSURE. |
| Selected response from:
 chris collister
France
Local time: 23:38
| Grading comment Ok thanks so much for your help here!
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The translation workplace 
peer agreement (net): +1
