244 



LIGHT 



Most of us are sufficiently familiar with mirrors to know 

 that the image is a duplicate of ourselves with regard to size, 

 shape, color, and expression, but that it appears to be back of 

 the mirror, while we are actually in front of the mirror. The 

 image appears not only behind the mirror, but it is also ex- 

 actly as far back of the mirror as we are in front of it ; if we 

 approach the mirror, the image also draws nearer ; if we with- 

 draw, it likewise recedes. 



The path of light. If a mirror or any other polished sur- 

 face is held in the path of a sunbeam, some of the light is re- 

 flected, and by rotating the mirror the reflected sunbeam may 

 be made to take any path. School children amuse them- 

 selves by reflecting sunbeams from a mirror into their com- 

 panions' faces. If the companion moves his head in order to 

 avoid the reflected beam, his tormentor moves or inclines the 

 mirror and flashes the beam back to his victim's face. 



If a mirror is held so that a ray of light strikes it in a per- 

 pendicular direction, the light is reflected backward along 



the path by which it came. 

 If, however, the light makes 

 an angle with the mirror, 

 its direction is changed, and 

 it leaves the mirror along a 

 new path. By observation 

 we learn that when a beam 

 strikes the mirror and 

 makes an angle of 30 with 

 the perpendicular, the beam 

 is reflected in such a way 



that its new path also 

 n angle of 



FIG. 113. -The ray AC is reflected as CD. 



the perpendicular. If the sunbeam strikes the mirror at an 

 angle of 32 with the perpendicular, the path of the reflected 



