Sunil Batra Solutions for Chapter: The Human Eye and the Colourful World, Exercise 1: Practice Exercise 5A

Describe the function of power of accommodation.

The far point of a person suffering from myopia is $4 \mathrm{m}$ from the eyes. Find the power of the corrective lens (in $\mathrm{D}$) he will have to use in order to see distant objects.

An old person has near point $100 \mathrm{cm}$. Find the power of the corrective lens (in $\mathrm{D}$) he will have to use.

The near point of a defective eye is $75 \mathrm{cm}$ from the eye. What is the power of the corrective lens (in $\mathrm{D}$) which enables him to read a book kept at the least distance of distinct vision?

Write the function of the following part of the human eye:
Iris

Write the function of the following part of the human eye:
Crystalline lens

Write the function of the following part of the human eye:
Ciliary muscles

With the help of ciliary muscles the human eye can change its curvature and thus alter the focal length of its lens. State the changes that occur in the curvature and focal length of the eye lens while viewing ($a$) a distant object  ($b$) nearby object.

Explain, why a normal eye is not able to see distinctly the objects placed closer than $25 \mathrm{cm}$, without putting any strain on the eye.