Electricians' operating and testing manual; (1910)
Horstmann, Henry C. [from old catalog], Tousley, Victor Hugo, 1875- [from old catalog] joint author · Chicago, F. H. Drake & co · leaf 236
concerned, de-pends upon its value as a means of discriminationboth as to form and color. The amount of light whichis useful for this purpose is known as the illumina-tion, and depends upon the quality and strength ofthe light giving source, and its distance from the ob-ject to be illuminated. The… … Figure 144 versely proportional to the square of its distance fromthe source of light. This is plainly shown in Figure144. If the surface A is so located that all points onit are at a distance of one foot from the one candle-power light L, the intensity of the light on this sur-face will be one…
Electrical engineering · Electric testing
Internet Archive · Library of Congress · Public Domain Mark 1.0. Free to use for anything.
