LIGHT, COLOR, AND SOUND 123 



the machinery is running at a high speed. Low speed gives 

 a low vibration, while high speed gives a quick vibration 

 It is possible to detect the difference in the sound produced 

 by two bodies of different composition, but with the same in- 

 tensity and pitch. The property of sound by which we are able 

 to distinguish this difference is called quality. Quality depends 

 upon the form of the vibrations. 



Questions 

 LIGHT AND COLOR 



1. Petroleum oil looks bluish green when it is on the water. 

 Why? 



2. Smoke and fine particles that float in the air deflect the 

 short waves of light more than the long ones. Why? Why is the 

 sky blue? Why is the sun red after a forest fire? 



3. Should colors that are to be worn in an artificial light be 

 selected by sunlight or by the artificial light? 



4. Why does a piece of red cloth appear black when seen by 

 blue light and red by red light? 



5. Why is it desirable to have school windows reach to the 

 ceiling? 



6. Why is it desirable to have the light for writing come over 

 your left shoulder? 



7. Tell the advantages of rough gray plaster. 



8. Why does a diamond sparkle? 



9. Upon what principles may imitation stones be made? 



10. When is a substance black? 



11. Is black a color? 



12. Is white a color? 



13. Why are white clothes worn in the summer? 



14. Why is a room with light walls better to work in than one 

 with dark walls, even when the same amount of light comes in the 

 room? 



15. Why do rivers appear shallower than the} r really are? 



