(3)

The least distance of distinct vision for a young adult with normal vision is 25 cm. The range of vision of a normal human eye is from infinity to 25 cm.

(3)

The change in focal length of an eye lens is caused by the action of the ciliary muscles. The ciliary muscles help in changing the shape of the lens, thus changing its focal length.

(2)

The image formed on the retina of the human eye is real and inverted. Then in the retina, the image is converted into electrical impulses and sent to the brain. The brain flips that image into a virtual and erect image.

(2)

White light is dispersed into its seven-color components by a prism. Different colors of light bend through different angles with respect to the incident ray, as they pass through a prism. So, the Violet light refracts the most while passing through a prism.

(2)

A small opening in the iris is known as a pupil. Its size is controlled with the help of the iris. It controls the amount of light that enters the eye.

(2)

The cornea refracts light entering the eye from external objects. It is the transparent layer forming the front of the eye.

(2)

Least distance of distinct vision for a normal human being is 25 cm. It varies with age. For infants, it is 5 to 8 cm. The human eye can distinguish about 10 million colors.

(3)

Presbyopia occurs due to progressive weakness of the ciliary muscles and decreasing eye lens flexibility.

(2)

Myopia is a defect of vision in which a person clearly sees all the nearby objects, but is unable to see the distant objects.

(1)

In hypermetropia, the image is formed behind the retina and a person cannot see nearby objects clearly. It can be corrected by using a convex lens. It helps in focusing the rays entering the eye on the retina.