| 摘要 |
PURPOSE:To easily and accurately measure a light speed in a school and a room by small-scale facilities by using an optical fiber which secures a long distance and can be stored compactly as a propagation path for light. CONSTITUTION:A half-mirror 12 changes the direction of light emitted by a light source 11, teeth 14 are arranged rotatably on the optical path 13 of the optical-path changed light so that teeth 14a and space 14b face each other, and an optical fiber 15 is arranged successively the teeth so that one end A faces the optical path 13 and the other end B faces a reflecting mirror 16. In this case, when the rotating speed of the teeth 14 is increased while the light beam is observed at the position of the eye, the light becomes unable to see. This results from that a gear 14 rotates while light passed between the gap E between teeth C and D travels forth and back between the ends A and B of the fiber 15 to enter a state shown in a figure (b) and the light is cut off by the tooth D. Consequently, the speed of the light is obtained and further, the optical fiber is used to easily a compact long-distance propagation path for the light.
|
