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HOW WE USE LIGHT 



Mixing Pigments. Mixing pigments such as paints 

 or dyes is quite a different matter from mixing colored 

 lights or light rays. If you mix blue and yellow paint, 



\ 



Why do only yellow rays appear at the right of this diagram ? 



green will result. A yellow pigment absorbs all the spec- 

 trum colors except yellow and green, while blue pigments 

 absorb all the spectrum colors except blue and green. 

 Green is the only color reflected by both pigments, and is 

 therefore the only color seen when the two are mixed. 



Color Blindness. In order to drive a locomotive, the 

 engineer must be tested for color blindness. There are 

 about three to four per cent of boys and about one per 

 cent of girls who cannot distinguish certain colors. They 

 are color blind. The most common form of color blind- 

 less is the inability to distinguish between red and green. 



SELF-TESTING EXERCISE 



Select from the following list those words which best fill the blank spaces 

 in the sentences below and arrange the words in proper numerical order. 

 A word may be used more than once. 



wave 



waves 



reflects 



light 



colors 



complementary 



darkness 



red 



green 



blue 



property 



refracts 



neutral 



normal 



violet 



white 



black 



length 



absorbs 



yellow 



pigments 



sensations 



supplementary 



length 



Color is a (1) of (2)_ 



length. The shortest (4). 



which is determined by its (3)_ 

 (5) gives the sensation 



of 



