Oct 15, 2008 11:26
15 yrs ago
1 viewer *
French term
La force de pression de radiation
French to English
Science
Science (general)
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!
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!
Proposed translations
(English)
| 4 +4 | force due to radiation pressure |
chris collister
|
| 4 +1 | the radiation pressure |
Diane de Cicco
|
| 4 | the strength of the radiation pressure |
Bashiqa
|
| 3 | Radiation Pressure Force |
mohanv
|
Proposed translations
+4
5 mins
chris collister
France
France
Native in English
Specializes in field
France
precision engineer, precision translator
Native in: English 
Works in: French to English
Related KudoZ points
:
20
Selected
force due to radiation pressure
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.
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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.
4 KudoZ points awarded for this answer.
Comment: "Ok thanks so much for your help here!"
7 mins
Radiation Pressure Force
Force de pression de radiation
Puisque les photons ont une quantité de mouvement, les photons qui composent un faisceau lumineux peuvent transférer cette quantité de mouvement aux atomes. Quand un atome absorbe et émet des photons, après un intervalle de temps la quantité de mouvement de l'atome change. Cette force est le résultat de ce que l'on appelle la force de pression de radiation. Cette force peut faire en sorte que l'atome accélère jusqu'à quelques milliers de fois l'accélération due à la gravité ou encore faire en sorte que l'atome ralentisse considérablement.
Radiation Pressure Force
Since photons have momentum, the flux of photons making up a beam of light can transfer momentum to atoms. As an atom absorbs and emits photons, the atom's momentum changes over time, giving rise to a force called radiation pressure. This force can cause an atom to accelerate at very high rates (as much as thousands of times the acceleration due to gravity) or slow it down considerably.
Puisque les photons ont une quantité de mouvement, les photons qui composent un faisceau lumineux peuvent transférer cette quantité de mouvement aux atomes. Quand un atome absorbe et émet des photons, après un intervalle de temps la quantité de mouvement de l'atome change. Cette force est le résultat de ce que l'on appelle la force de pression de radiation. Cette force peut faire en sorte que l'atome accélère jusqu'à quelques milliers de fois l'accélération due à la gravité ou encore faire en sorte que l'atome ralentisse considérablement.
Radiation Pressure Force
Since photons have momentum, the flux of photons making up a beam of light can transfer momentum to atoms. As an atom absorbs and emits photons, the atom's momentum changes over time, giving rise to a force called radiation pressure. This force can cause an atom to accelerate at very high rates (as much as thousands of times the acceleration due to gravity) or slow it down considerably.
Reference:
http://inms-ienm.nrc-cnrc.gc.ca/research/cesium_clock_f.html
http://inms-ienm.nrc-cnrc.gc.ca/research/cesium_clock_e.html
+1
7 mins
Diane de Cicco
France
France
Native in French
&
English
Specializes in field
France
Specialty: Biology, Chemistry, Medicine
Native in: English 
, French
Works in: English to French, French to English
the radiation pressure
I think this suffices :
"The radiation pressure depends on whether the radiation is absorbed or reflected . If it is reflected, the object which reflects it must recoil with enough ..."
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Note added at 8 mins (2008-10-15 11:34:57 GMT)
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since pressure IS a force
"The radiation pressure depends on whether the radiation is absorbed or reflected . If it is reflected, the object which reflects it must recoil with enough ..."
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Note added at 8 mins (2008-10-15 11:34:57 GMT)
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since pressure IS a force
Peer comment(s):
| agree |
Drmanu49
: Yes, force would seem redundant. Hi SDDC!
48 mins
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Thanks
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| neutral |
chris collister
: Force and pressure, although proportional, are definitely NOT the same thing. There may not be much force at the end of a needle, but the pressure is huge. Expl: pressure=force/area. Applies to any force, eg radiation, hydraulic, mechanical etc.
1 hr
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Oui, donc "la force de pression" ne veut rien dire. Il s'agit de la pression résultant d'une force appliquée pour une surface donnée
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10 mins
the strength of the radiation pressure
Bodies such as the sun radiate, which has an inherent pressure. Maxwell's theory in 1871
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