120 



REFRACTION' 



where AC and AO meet after refraction will be the position 

 of the top of the arrow. Similarly it can be shown that the 



center of the arrow will 

 be at the point T, and 

 we see that the image 

 is larger than the ob- 

 ject. This can be 

 easily proved experi- 

 mentally. Let a con- 

 vex lens be placed 



FIG. 74. Rays above O are bent downward, those near a Candle (Fig. 75 )> 

 below O are bent upward, and rays through O mnvp naner srrpen 

 emerge from the lens unchanged in direction. 



back and forth be- 

 hind the lens; for some position of the screen a clear, enlarged 



image of the candle will be made. 

 If the candle or arrow is 



placed in a new position, say at 



MA (Fig. 76), the image formed 



is smaller than the object, and 



is nearer to the lens than it 



was before. Move the lens so 



that its distance from the candle 



is increased, and then find the 



image on a piece of paper. The size and position of the image 



depend upon the distance 

 of the object from the 

 lens (Fig. 77). By means 

 of a lens one can easily 

 get on a visiting card a 

 picture of a distant church 

 steeple. 

 115. The Value of Lenses. If it were not for the fact that 



a lens can be held at such a distance from an object as to 



FIG. 75. The lens is held in such a 

 position that the image of the candle 

 is larger than the 6bject. 



A C 



FIG. 76. The image is smaller than the object. 



