Light 



183 



Card Boa 



Each point of light in the candle flame casts a shadow. The 

 light from the top of the flame casts one shadow, the light from 

 the bottom another, and so on. These different shadows over- 

 lap and form a dark space 

 near the center of the shadow, 

 known as the umbra. Around 

 the umbra is a somewhat 

 lighter space, the penumbra, 

 formed by light from one part 

 of the flame falling on the 

 shadow cast by another part. 



Reflected Light. When- 

 ever light strikes an object, 

 some of the light is absorbed 



and some is turned back to us, unless the object is black. A 

 black object will absorb all of the light and none will be turned 

 back. When light is turned back it is said to be reflected. The 

 path over which the light is reflected is fixed. This path is deter- 



Candle 



Penumbra- 



How A SHADOW is FORMED 



REFLECTION OF LIGHT RAYS 



Notice the difference .in the manner of reflection from smooth and from rough surfaces. 



mined by the angle at which the light strikes the reflecting surface. 

 The angle at which the light strikes a plane surface is equal to 

 the angle at which it leaves it. 



Mirrors. A mirror is a very smooth surface which reflects 

 light. Mirrors are usually made either by polishing a piece of 

 metal, as those often seen in camping outfits, or by covering one 

 side of a piece of glass with silver or a mixture of mercury and 



