Chapter 18, Problem 91A

To determine

To explain: The reason for better focusing in bright light.

Explanation of Solution

Introduction:

Spherical aberration is a kind of aberration observed in an optical systems which uses spherical mirrors or lenses. The light rays that are incident on the outer edge of the lens are reflected or refracted more or less compared to that incident light which is close to the central portion of the lens. Due to this deviation in reflected or refracted light rays the quality of image produced is not good. That is, the image produced is slightly blurry.

The light that enters the eye is mainly focused by the cornea that is the surface of the eyes.

Some of the light rays incident on the cornea are gets refracted at larger angles but they are taken off by an iris of the eyes. Hence all the rays converges at a narrow angle and there is less spherical aberration. Therefore the eyes can focus better in bright light.