128 LIGHT 



Since illuminated objects are seen only by the waves 

 that they reflect to the eye ( 126), clearly the color of 

 such bodies will depend upon (1) the colors of waves that 

 fait upon them, and (2) which of these waves they reflect. 

 When the light upon an illuminated object is white 

 light, the object will appear white if all the waves are 

 reflected; if none of the waves are reflected from the 

 object, but all are absorbed, it is said to be black ; if all 

 the waves pass through a body, being neither reflected 

 nor absorbed, the substance is called colorless. In the 

 great number of colored objects, however, part of the 

 waves are absorbed while others are reflected; the color 

 of such substances depends upon the color of the waves 

 that are reflected. f 



QUESTIONS 



1. Is color a property of objects or of light waves? Why do 

 different objects seem to be of different colors ? 



2. Upon what does the color of a light wave depend? Do waves 

 of different colors ever unite in one beam? What is white light? 



3. What is a spectrum? Explain how a spectrum is formed 

 when light waves pass through a prism. 



4. How many distinct colors in the spectrum of white light ? 

 Name them in order. Which has the fastest and which the 

 slowest vibration rate ? 



5. What is a rainbow ? How is a rainbow formed ? When 

 and where do rainbows generally appear? 



6. Explain why light waves seem to change color on passing 

 through certain substances. Why does the sun often appear red 

 at sunset? Why is this more often true in hot, dry weather? 



7. Upon what two factors may the color of an object depend ? 

 In sunlight, what objects appear white? black? colorless? What 

 objects seem red ? green ? blue ? 



8. Is black a color ? How are black objects perceived ? 



