Question

(a) Draw a simple diagram of the human eye and label clearly the cornea, iris, pupil, ciliary muscles, eye-lens, retina, optic nerve and blind spot.
(b) Describe the working of the human eye with the help of the above diagram.
(c) How does the eye adjust itself to deal with light of varying intensity?

Answer 1

Iris Controls Light Intensity

Explanation:

• (b) Working of the human eye

1. The light rays coming from the object kept in front of the eye enter the cornea, pass through the pupil and fall on the eye lens.
2. The eyes lens is a convex lens, so it converges the light rays and produces a real and inverted image of the object on the retina.
3. The image formed on the retina is conveyed to the brain by the optic nerve and gives rise to the sensation of vision.

• (c) Since the light intensity varies but the iris helps the eyes to adjust the pupil size as per the light intensity being received. Large Light Intensity Contracts iris thereby reducing light into eyes and Vice versa.