404 



REFRACTION OF LIGHT. 



FIG. 307. 



This focus will be virtual. Conversely, converging rays falling 

 upon a convex lens will form a focus nearer the lens than the 

 principal focus. (See Fig. 307.) 



626. Conjugate Foci of Concave Lens. 



Rays from a luminous point at any distance whatever will 

 be made more divergent by passing through a concave lens. 



FIG. 308. 



Rays parallel to the principal axis will diverge after refrac- 

 tion as if they proceeded from the principal focus. In 

 any case, the focus will be virtual, and nearer the lens than 

 the luminous point. 



627. Images Formed by Convex Lenses. 



The analogies between the convex leris and the concave 



