LIGHT AND COLOR 



357 



and the wall or paper. Do all the colors of the spectrum still 

 appear ? Repeat the experiment with glasses of other colors. What 

 happens? 



It was seen in Experiment 106 that when white light is 

 passed through a prism it not only suffers a change in direc- 

 tion (is refracted), but it is also separated into different 

 colors. White light must then be made up of lights of 

 different colors, and the prism must have affected these 

 colors so that each was bent to a different extent in passing 

 through the glass. (Figure 107.) Careful experiments show 



\ 



FIGURE 107 



that light is a form of wave motion, and that the infinitesi- 

 mally small wave-lengths of the various colors differ from 

 one another. The colors are refracted differently in passing 

 through the prism and are therefore separated from one 

 another. The band of colors into which white light is 

 separated by the prism is called the spectrum. 



It was also seen that if the light from the prism was passed 

 through red glass, all the colors except the red were cut off, 

 or absorbed. If we could have made a careful test of the 

 glass we should have found that it had been warmed by the 

 absorption of these colors; that is, the energy of light had 

 been transformed into the energy of heat. When light is 



