Schematic of the Fizeau apparatus

Schematic of the Fizeau-Foucault apparatus and the improvement by Michelson. The original setup used a less brilliant light source, so that a clear scale had to be used so that one could stare into the beam.

The Fizeau–Foucault apparatus (1850) was designed by the French physicists Hippolyte Fizeau and Léon Foucault for measuring the speed of light. For the game see 1850 (board game. 1850 ( MDCCCL) was a Common year starting on Tuesday (link This article is about the country For a topic outline on this subject see List of basic France topics. Physics (Greek Physis - φύσις in everyday terms is the Science of Matter and its motion. Armand Hippolyte Louis Fizeau (1819-1896 French physicist, was born in Paris. Jean Bernard Léon Foucault (ʒɑ̃ bɛʁnaʁ leɔ̃ fu'ko ( 18 September 1819 &ndash 11 February 1868) was a French physicist The apparatus involves light reflecting off a rotating mirror, toward a stationary mirror some 20 miles (35 kilometers) away. Light, or visible light, is Electromagnetic radiation of a Wavelength that is visible to the Human eye (about 400–700 A rotation is a movement of an object in a circular motion A two- Dimensional object rotates around a center (or point) of rotation A mirror is an object with a surface that has good Specular reflection; that is it is smooth enough to form an Image. As the rotating mirror will have moved slightly in the time it takes for the light to bounce off the stationary mirror (and return to the rotating mirror), it will thus be deflected away from the original source, by a small angle.

Foucault based his apparatus on an earlier experiment by Fizeau who, in 1849, used two fixed mirrors, one partially obscured by a rotating cogwheel. Year 1849 ( MDCCCXLIX) was a Common year starting on Monday (link will display the full calendar of the Gregorian calendar (or a Common Fizeau's value for light's speed was about 5% too high.

External links

• Speed of Light Formal Report (The Foucault Method)