392 REFLECTION OF LIGHT. 



4. (a.) What kind of mirror always makes the image smaller that 

 the object? (6.) What kind of a mirror may make it larger or 

 smaller, and according to what circumstances ? 



5. Rays parallel to the principal axis fall upon a convex mirror. 

 Draw a diagram to show the course of the reflected rays. 



6. (a.) Why do images formed by a body of water, appear in- 

 verted? (6.) What is the general effect of concave mirrors upon 

 incident rays ? 



7. A person, placed at a considerable distance before a concave 

 mirror, sees his image, (a.) How does it appear to him ? He ap- 

 proaches the mirror and the image changes. (&.) Describe the 

 changes that take place until he sees a virtual image of himself. 



8. A man stands before an upright plane mirror and notices that 

 he cannot see a complete image of himself, (a.) Could he see a 

 complete image by going nearer the mirror? Why ? (&.) By going 

 further from it ? Why ? 



9. When the sun is 3(T above the horizon, its image is seen in a 

 tranquil pool. What is the angle of reflection ? 



10. A person stands before a common looking-glass with the left 

 eye shut. He covers the image of the closed eye with a wafer on 

 the glass. Show that when, without changing his position, he 

 opens the left and closes the right eye, the wafer will still cover the 

 image of the closed eye. 



11. The distance of an object from a convex mirror is equal to the 

 radius of curvature. Show that the length of the image will be 

 one-third that of the object. 



Recapitulation. In this section we have, considered 

 the Nature and Laws of Reflection; Dif- 

 fused and Invisible light; the Apparent Direc- 

 tion of bodies; Images formed in Plane Mirrors 

 and their Construction ; Concave Mirrors, 

 their Effects, Principal and Conjugate Foci; 

 Images formed by them with their Construction, 

 Projection and Description; foci and images for 

 Convex Mirrors. 



