Optics. Jean Bernard Foucault

you are: Optics

To Check up result of Ryomera terrestrial means it seemed impossible. Even at distances in some kilometres it was necessary to measure intervals of time of an order of million fractions of a second, and any equipment of such accuracy in XVII and XVIII centuries were not. Gradually, as people seized materials and technology, became almost possible and terrestrial measurements of a velocity of light. светильник жку 250 и светильник жку телефон москва и область .

The First such measurements were executed approximately in 1850 rantsuzskie by physicists Armand Ippolit Lui from (1819-1896) and Jean Bernard Foucault (1819-1868). Both of them used exclusively fast rotation which became possible thanks to creation of the strong alloys maintaining huge centrifugal explosive forces.

In device Fizo there was a cogwheel which interrupted a thin ray of light before reflexion from a remote mirror. In Foucault's device the rotating mirror was used; if the mirror turned on an appreciable corner for time spent by light on passage of a way to a remote mirror and back it would be possible to register displacement of the image of a source. Results of both these measurements have appeared in the consent with conclusions of Ryomera. Installation of Fizo could be applied at lengths of a course of a light beam some km, and Foucault's device - at distances only to 20 m, that is a way Foucault is more convenient. Foucault could measure a velocity of light in water also; he has found out that it is less, than in air, and it marked itself definitive defeat of the corpuscular theory of light.

Thus, by 1850 the basic properties of light became already known: light - wave movement with very small length of a wave, an order of 5•10-5 sm; fluctuations in waves the cross-section; for light distribution no material environment is necessary, and it extends with a speed about 3•1010 sm a second.