Chapter 18, Problem 69A

To determine

To explain: The process of focussing the light from eyes.

Explanation of Solution

Introduction:

The converging lenses and mirrors are commonly used to focus the light to a point. The light rays travelling parallel to the optical axis strikes the converging lens or mirrors ans are converges in to a point called focal point of that lens or mirror.

The light that enters the eye is mainly focused by the cornea (that is the surface of the eyes). It is a dome shaped lens (as shown in figure 1) and it starts the process of light focusing. About sixty percent of the focusing power of the eyes are contributed by the cornea. Fine focusing of light take place by changing the shape of the lens that is done by the contracted muscles in the eyes, permitting the eyes to focus on the objects under observation (which may be near or far from the eyes of an observer).

  

Figure 1