» Rotating Mirror (0292)
Immagini
DESCRIPTION
Exhibit 292 is a rotating mirror complex consisting of eight rectangular mirrors in an octagon cage which is rotated by a motor operating below the three legged base. This type of rotating mirror was used by Albert Michelson to measure the velocity of light in air in 1926 using the scheme and notation in figure 1. The procedure starts with the mirror at rest and a beam of light from the source S which is defined by the narrow slit and that then follows the path S, A, M1, M2, C1, C2, C3, C2, C1, M3, M4, B and then the prism and telescope. If face 1 is at A, B is at face 5. The same image of the source is visible in the telescope as the wheel begins to turn such that the reflection from face 1 at A is followed by face 6 at B (1/8 of a revolution). Then the rotational velocity of the wheel is doubled so that the reflection at face 1 at A is followed by face 7 at B (1/4 os a revolution). By knowing the rotational velocity of the wheel and the distance involved, Michelson measured the speed of light in air to be 2.9979 1010 cm s-1. The experiment had C1 on Mount Wilson and C2 on mount Sant'Antonio, at a distance of about 35 km.BIBLIOGRAPHY
- [1] Eligio Perucca," Fisica Generale e Sperimentale"; Vol. II, Quarta edizione, UTET Torino, 1942-XX, pag. 168.
- [2] Jenkins and White, "Fundamentals of Optics", 3rd Ed. McGraw-Hill Book Company, INC. 1957. Pag. 389.
Dati Catalografici
| Data di costruzione: | --- |
|---|---|
| Data di carico: | 1933-10-10 |
| Nr. Inventario: | 4653 (Generale dal 1874) |
| Costruttore: | Costruttore sconosciuto |
| Materiale: | vetro, metallo |
| Dimensioni: | Larghezza degli specchi: 6,5 cm, altezza: 23 cm; Diametro della base: 13 cm; Altezza complessiva: 40 cm |
| Conservazione: | buono (Manca la cinghia. Uno specchio è staccato, e uno è un po' incrinato.) |