Question

Automatic focusing is done by human eye by

• A. Changing the convexity of the eye surface
• B. Changing the thickness of the fluid in the eye
• C. To and fro motion of the eye
• D. To and fro motion of the retina

Answer 1

The correct option is A

Changing the convexity of the eye surface

Explanation for correct answers:

Option A

1. The human eye has an adaptability to observe objects at a close distance as well as at infinity.
2. This automatic adjustment feature is possible due to a change in the convexity of the convex lens.
3. Due to this change, the focal length changes and allows us to observe objects at a variety of distances.
4. This is done with the help of ciliary muscles, which when apply tension changes the shape of the lens

The explanation for incorrect answers:

Option (B) Changing in the thickness of the fluid in the eye -

It is a result of damaged blood vessels in the retina. It helps to keep the retina intact .

Option (C) To and fro motion of the eye -.

It helps the brain to get a better understanding of the surroundings and helps the individual to view a larger area

Option (D) To and fro movement of retina -

the retina is the screen on which the image is formed to and fro movement of it results in blurry vision

Hence, the correct option is (A), changing the convexity of the eye surface.