446 



CONCAVE MIRRORS. 



fleeted towards the focus/; the ray Ace, which passes 

 through c, the centre of curvature, is reflected upon 

 itself, that is in the direction e c; both directions in- 

 tersect in a; hence at a is the position of the image 

 of A. The rays B g and B c h which proceed from B 

 are reflected in directions gf and h c ; these intersect 

 in b ; hence b is the image of B. All points between A 

 and B produce images between a and b ; hence a b is 

 the image of the object A B. I The image of an object 

 whose distance from the mirror is greater than twice the 

 focal length is formed between the focus and the centre of 

 curvature, is inverted, smaller than the object, and real. ) 



From the law of the equality of the angl esof in- 

 cidence and reflection it follows immediately that rays 

 proceeding from the points a and b would form images 

 respectively 'at A and B, and that A B would then 

 Vecome the image of an object a b. (The image of an 



FIG. 252. 



object between the focus and the centre of curvature is 

 formed at a distance from the mirror greater than twice 

 the focal length, is inverted, larger than the object, and real. 

 The same result may be found in a different manner. 

 Let A B, fig. 252, be again the object, c and / the 



