Question

 Explain the functions of the following parts of the eye:
(i) cornea
(ii) iris
(iii) pupil
(iv) ciliary muscles
(v) eye-lens

Answer 1

Functions of the parts of the eye:
(i) Cornea: The front part of the eye that is made of a transparent substance and is convex in shape is called the cornea. The light from an object enters the eye through the cornea.

(ii) Iris: The iris is a flat, coloured and a ring-shaped membrane with a hole in the middle called the pupil. The iris regulates and controls the amount of light entering the eye by automatically adjusting the size of the pupil according to the intensity of light that the eye receives.

(iii) Pupil: The pupil is a hole in the middle of the iris and appears black because there is no light reflected from it. The pupil expands or contracts to regulate the amount of light entering the eye.

(iv) Ciliary muscles: The ciliary muscles contract or relax the eye lens and help in changing its focal length to focus the images of nearby or distant objects on the retina.

(v) Eye lens: The eye lens is a convex lens whose main function is to the converge the light rays from an object and form a real and inverted image of the object on the retina.