WHAT ARE SOME OF THE PROPERTIES OF LIGHT? 135 



Bodies Vary in Ability to Transmit Light. Have you 

 ever noticed how the " steaming 7 ' of a window at home or 

 on the train changes your vision of objects on the other 

 side? If you wear glasses, perhaps you have noticed 

 that when you come into a warm, damp atmosphere 

 from the cold outdoors the moisture gathered upon your 

 glasses so that you could not see anything distinctly. 

 When you wiped off the moisture or it disappeared after 

 the glasses were warmed you could see clearly again. 

 Clear glass lets light go through without much change in 



Explain the terms transparent, translucent, and opaque by reference to the 



diagram. 



direction. All bodies like glass, cellophane, quartz, air, 

 and water which permit light to pass through so that we 

 can see objects through them clearly are called transpar- 

 ent. Making the surface of glass rough causes a scatter- 

 ing of light that passes through. Frosted glass, con- 

 densed vapor on glass, oiled paper, and very thin paper, 

 gauze, or window shades may allow enough light to pass 

 through to show the presence of objects without their 

 being seen distinctly. These bodies are translucent. 

 Objects that cut off all light are called opaque. 



A Shadow. If you darken a room and allow a beam of 

 light to enter, you will notice that it travels in a straight 



