Laurence, Lionel · London, School of Optics · leaf 26
Fig. 8. ground, the shadow has an outline corresponding to that of the body, becausethen, as in Fig. 8, the periphery of B cuts off the light equally in every direc-tion. The shape of the shadow otherwise depends on the inclination of thescreen to the opaque body and the source of light. … Fio. 9. In general the shadow (Fig. 9) exhibits a dark centre u u called theumbra, from which the light is entirely cut off, and a less black outer portionPu, Pu, called the penumbra, which receives a certain amount of illumination.The space Pu receives light from S, but none from S, while Pu…
Optics
Internet Archive · Gerstein Library, University of Toronto · Public Domain Mark 1.0. Free to use for anything.
