Draw a labelled sketch of the human eye. Explain the function of the following parts of the human eye: (a) cornea (b) iris (c) pupil (d) eye lens (e) ciliary muscles (f) retina (g) optic nerves.
(a) cornea: Its main function is to act as a protective layer for the eye.
(b) iris: The iris is responsible for the characteristic colour of the eye of a person.
(c) pupil: Pupil is the self-adjustable aperture which regulates the amount of light entering the eye by adjusting its size.
(d) eye lens: The eye lens is a convex lens which focuses the rays of light on retina.
(e) ciliary muscles: These muscles help in changing the curvature and the focal length of the eye lens.
(f) retina: It is a light sensitive screen where image of the object is formed.
(g) optic nerves: Carries signals from the eye to the brain.