Third Dimension Movies And E X P A N D E D Screen (1953)

51* THREE-DIMENSIONAL MOTION PICTURES Less comnxonly observed but easily verified is the influence exerted upon the intensity of the reflected light by the obliquity of the Incident ray In respect to the reflecting surface. If we stand on the shore of a large body of water, such as a tranquil lake, we can readily observe that at high noon when the sun Is unit of light pun its of area The level of illumination varies inversely as the square of the distance from the light source to the surface approximately at the zenith we can look at the water without being disturbed by any glaring reflection. As the sun nears the horizon the reflected light becomes stronger and stronger till In the late part of the day the light glare from the water is so intense that the eye can hardly look directly at it. REFRACTION OF LIGHT When a ray of light which is being propagated In a medium of a certain density encounters a transparent medium of a dif ferent density It passes through it, but its course is deviated. This phenomenon is called Refraction. The light that is refracted is as in the case of reflection, of less intensity than the Incident light, due to the fact that a small portion of it is reflected by the boundary surface, some of it is scattered and some of it is absorbed by the refracting medium. It has been stated previously that Foucault has proved con clusively that light suffers a diminution of Its velocity when passing from a medium of certain density into a medium of greater density. This diminution of velocity is due to a constant dying away of the light waves while they pass through such dense medium