$(i)$ Calculate the maximum power of accommodation of a person having normal vision.
$(ii)$ $A$ person needs to use glasses for reading a newspaper. Identify the defect in her vision and the type of lens she would need to correct it.
$(iii)$ Sometimes when we enter a dark room from bright sunlight,we are unable to see objects clearly. Why?

(A) $(i)$ The near point of a normal eye is $D = 25 \text{ cm}$. The power of accommodation $P$ is given by $P = 1/f = 100/D$ (where $D$ is in cm).
$P = 100 / 25 = 4 \text{ D}$.
Thus,for a person with normal vision,the power of accommodation is about $4 \text{ Dioptre}$.
$(ii)$ The defect is Hypermetropia (long-sightedness),as the person has difficulty reading nearby objects. She would need a convex lens to correct this defect.
$(iii)$ The pupil regulates and controls the amount of light entering the eye. In bright sunlight,the pupil size is small. When we enter a dark room,it takes some time for the pupil to dilate (expand) to allow more light to enter,which is why we cannot see objects clearly immediately.