WHAT IS COLOR? 159 



VIII. You are on one side of a stream of quiet water and see a 

 large oak tree on the other side. The sun shines brightly and 

 lights up the side of a tree towards you : (29) you see a real image 

 of the tree in the water ; (30) there is also a shadow of the tree on 

 the water; (31) as you see the image, the tree appears upside 

 down ; (32) the image is unreal. 



IX. The eye " focuses " or makes the image on the retina 

 clear by : (33) changing the distance between the retina and lens ; 

 (34) changing the thickness of the lens ; (35) changing the size of 

 the pupil; (36) by a process called "accommodation." 



X. A blue dress appears blue in daylight because : (37) the 

 material absorbs only blue light from the sunlight ; (38) the 

 material absorbs all the sunlight except blue; (39) its own color 

 added to sunlight gives blue ; (40) it gives out blue color of its 

 own which is stronger than the white of sunlight. 



THOUGHT QUESTIONS 



1. Why are lamp shades made of opal glass? 



2. Why are electric light bulbs frosted ? 



3. Why are offices in large buildings often inclosed in trans- 

 lucent glass? 



4. Make a list of the objects you saw on your way to school 

 that showed regular reflection. 



5. How would you point a stick to a given point at the bottom of 

 a dish of water if your stick has to enter the water at an acute 

 angle ? 



6. Compare a real and an unreal image and show how you 

 would make each. 



7. Why do the re- 

 flectors used for auto- 

 mobile headlights have 

 the shape shown in the 

 illustration ? 



8. Why is the image 

 seen in the back of a 

 camera inverted but that 



seen in the finder up- 



right? 



9. What happens to a beam of bright sunlight by which you 

 see the white sand on the beach: first without glasses and later 

 through amber sun glasses ? 



10. Why is it difficult for you to write your name while looking 

 at your hand, pencil, and paper only in the mirror ? 



