Laurence, Lionel · London, School of Optics · leaf 30
of a sphere is equal to i^x2, r being the radius. Now if the radius ofthe spherical envelope be increased from one foot to two feet, i.e. doubled,its area will be quadrupled, and therefore the available light is distributedover 4 times the area and the amount of light received on each point ofthe… … The Law of Inverse Squares.—Since a flat surface virtually forms a portionof a sphere having the source of light for its centre, it may also be stated,without much error, that the illumination of a flat surface varies inverselywith the square of its distance from the source of light. This is…
Optics
Internet Archive · Gerstein Library, University of Toronto · Public Domain Mark 1.0. Free to use for anything.
