Question

Question #bcb77

Answer 1

The pupil controls the amount of light entering the eye. The lens helps to focus the light into a sharp image on the back of the eye (the retina).

Explanation:

The pupil is really nothing more than an opening formed in the centre of the iris (the coloured part of the eye). As such, it acts like the `f`-stop on a camera. When open wider, more light enters (this happens automatically in a dark room). When it closes down (as on a sunny day) it limits the light that enters to protect the light-sensitive tissues inside.

The lens is part of the system (including the cornea) that acts like the part of the camera with the same name. It causes the rays of light upon entering the eye to be bent in such a way that a focused image appears at the back of the eye.