LIGHT 



273 



188. Lenses. Converging lenses are thick in the 

 center and thin at the edge. The light which passes 

 through them is refracted or bent from its straight path 



LENSES 

 a, b, and c, are Converging, and d, e, and/, Diverging Lenses. 



so that it will pass through a point. These lenses are 

 used in simple magnifying glasses, microscopes, tele- 

 scopes, cameras, and in eye-glasses for farsighted people. 



Diverging lenses are thin in the center and thick at 

 the edge. The light which passes through them is made 

 to diverge or spread apart. They are used in eye-glasses 

 for people who are nearsighted, and sometimes they are 

 used in the small end of opera glasses. 



189. Cameras. With a pin or pencil make a small 

 hole in a sheet of paper and hold it before a light or 

 toward a win- 

 dow; place back 

 of the hole an- 

 other sheet of 

 paper, and on it 

 you will see a 

 picture or image 

 of the object 

 from which the 



light is coming. This is known as a "pin hole" camera. 

 A picture can be taken with it if a light-tight box is 



FORMATION OF A PINHOLE IMAGE 



