42 ANSWERS TO PRACTICAL QUESTIONS 



Wliy are the colors reversed ? 



We can understand this by looking at Fig. 164. In one 

 bow we cee that the rays enter the drops at the top, and are 

 refracted at the bottom to the eye ; in the other, that the rays 

 enter at the bottom, and are refracted at the top to the eye. 



2. WJiy can we not see around a house or through a 

 bent tube ? 



The rays of light move in straight lines. 



3. What color would a painter" use if he wished to rep- 

 resent an opening into a dark cellar ? 



Black. 



4. Is black a color ? 



Np ; it is the absence of light, and hence of color. 

 Is white ? 



No. It is the result of mixing a multitude of tints, each of 

 which loses its individuality as color by union with the rest. 



5. By holding an object nearer a light, ivill it increase 

 or diminish the size of the shadow ? 



It will increase it, because more rays are intercepted. 



7. Where should ^ve look for a rainboiv in the morn- 

 ing ? 



In the west. 



<V. Can two spectators see the same rainboiv ? 



They can not, because no two persons can be at the right 

 angle to get the same color from a drop. 



9. Wliy, tvhen the drops of ivater are falling through 

 the air 9 docs the bow appear stationary ? 



Because amid the multitude of drops there are always some 

 in the right direction. 



10. Why can a cat see in the night better than a human 

 being ? 



