240 



LIGHT IN THE HOME 



a piece of oiled paper or ground glass, if placed in front of 

 the candle, allows a certain amount of light to go through, 

 but we cannot see the flame distinctly. Such a sub- 

 stance is called a translucent 

 body. If we now take a board 

 or piece- of sheet metal and hold 

 it before the light, it prevents 

 any light from reaching our eyes. 

 Such a substance is called an 

 opaque body, and behind such a 

 body, the space from which light 

 is excluded is called a shadow. 

 Light passes through transparent 

 bodies without much loss or 

 scattering of the rays. Less 

 light passes through translucent 

 bodies, and there is much scat- 

 tering of the rays of light, while 

 no light at all passes through 

 opaque bodies. 



Which obstructs the most light? 

 Which the least ? 



Experiment. Transparency. 



Hold glass, oiled paper or ground glass, and sheet metal in turn between 

 your eyes and a light. Explain the different effects. 



Reflection and its reasons. If you take a smooth 

 surface, such as a mirror, and allow light to fall on it, a 

 strong beam is reflected, while from a roughened surface 

 no such beam passes, the light being scattered from the 

 irregular surface, or diffused. It has long been known 

 that light striking a flat smpoth surface would be reflected 

 from it at exactly the angle at which it strikes it. If, 

 in a beam of sunlight the rays which travel parallel to each 



