LIGHT 



10. The Light We Receive from the Sun. 



Just after sunrise and just before sunset we may look 

 at the sun without hurting our eyes. The sun looks 

 large and red. The reason it looks large is because we 

 can compare its size with the size of other objects, and 

 when we notice that it appears larger than a distant house 

 or tree we realize that it is very large. The sun appears 

 red because the light in coming along the surface of the 

 earth has passed through a large amount of dust and fine 

 drops of water, which have sifted the light until most of 

 its strength has been taken out. 



As the sun mounts higher and higher in the sky, the 

 light passes throueh less and less of the fine particles, 

 and we say the light becomes brighter. On hazy days, 

 or when there is smoke in the air, the sun looks red even 

 at noontime. To show that the reason why the sun ap- 

 pears red is because the light is sifted, we can perform 

 the following experiment. 



Experiment 11. The Appearance of the Sun through 

 Smoked Glass. 



Apparatus: Glass, candle. 



a. Hold a piece of ordinary window glass in the 

 flame of a candle or the flame of a kerosene lamp, moving 

 the glass around in order to distribute the smoke. Tf 

 the glass is held still in the flame it will break. Smoke 

 one side only. The material on the glass is soot. 



b. Hold the smoked glass between the sun and one 

 of your eyes, closing the other one. How does the sun 

 appear? Move the glass so that you look through more 



