Convex Lens Focuses Light Rays.
Figure 49-2 shows parallel light rays entering a convex
lens. The light rays passingthrough the center of the lens strike the lens exactly perpendicular to the
lens surface and, therefore, pass through the lens without being refracted. Toward either edge of the
lens,
Wave fronts A B Glass Figure 49-1 Light rays entering a glass s rface perpendicular to
the light rays (A) and a glass surface angulated to the light rays (B). This figure demonstrates
that the distance between waves after they enter the glass is shortened to about two-thirds
that in air. It also shows that light rays striking an angulated glass surface are bent. Figure 49-2 Bending of light rays at each surface of a convex spherical lens, showing that parallel
light rays are focused to a focal point.Unit X The Nervous System: B. The Special Senses598
however, the light rays strike a progressively more angulated interface. The outer rays bend more and
more toward the center, which is alled convergence of the rays. Half the bendingoccurs when the rays
enter the lens, and half as they exit from the opposite side
