THE ACTION OF LIGHT 



word — than others. Water is more dense than air 

 and glass than either. The bending of light rays is 

 known as refraction. So now we may state our 

 second law a little more concisely, thus : — When 

 light passes from a medium into one more dense, 

 or vice versa, it is refracted, and the more dense 

 the medium into which or from which the light 

 passes the greater the refraction. 



A diagram and an experiment should make 

 matters clear. Suppose AB is a ray of light travel- 



ing in air and that it falls on a sheet of water, 

 WXYZ, the ray will be bent along BC and its course 

 from air to water may be represented by ABC. 

 Suppose again, WXYZ represents, not water but 

 glass; as glass is more dense than water the course 

 of the ray AB is represented by ABD, it is refracted 



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