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GENEKAL SCIENCE 



3. Why do you not see an image when you look at paper? 



4. Why is well-glazed paper bad for the eyes? 



5. Why is it possible to see an image in a window? 



6. Why is it difficult to look into a room from the outside through 

 a window when the sun is shining brightly? 



7. Why do you shield the face with the hand when you wish 

 to look into a room from the outside through a window when the 

 sun is shining brightly? 



8. How does the submarine captain see objects on the surface 

 of the water by the aid of the periscope? 



9. Why is it necessary to have parabolic mirrors in search 

 lights? 



10. What have you about your home in which curved mirrors 

 are used? Explain why. 



REFRACTION 



Refraction of Light. If a pencil is placed in a dish of water and 

 looked at from one side it will appear to be broken or bent. This 



FIG. 203. 



FIG. 204. How the light rays are bent 

 in passing through a prism. 



is due to the light rays entering the water, which is a denser medium 

 than the air. When light rays enter a denser medium they are 

 bent downward, causing objects to appear larger, or bent, or broken. 

 A coin placed at the bottom of a dish full of water seems to be 

 higher up, and if a person looks directly over the edge of the dish, 

 it is possible to see two images of the coin at the same time. The 

 image of the sun is seen before the sun rises, because of the rays 

 of light which are refracted by the light entering the air, a denser 

 medium than that in which it was traveling before it came in con- 



