Question

A boy reads book from 25 cm distance (minimum
distance of distinct vision), then
1) Eye lens becomes thin and ciliary muscles are
contracted
(2) Focal length of eye lens is minimum and ciliary
muscles are relaxed
(3 Focal length of eye lens is minimum and ciliary
muscles are maximum contract
(4) Focal length of eye lens is maximum and ciliary
muscles are relaxed
focal length​

Answer 1

Focal length of eye lens is maximum and ciliary  muscles are relaxed.

Option (4) is correct.

Explanation:

• The human eye has a natural lens with its own focal length.  
• The human eye can see a minimum distance of 25 cm.
• Around the lens of the human eye, ciliary muscles are attached that can change the focal length accordingly.
• The focal length can be adjusted by expanding or contracting the lens.
• When ciliary muscles are stretched the lens becomes thin and vice versa.