Define the term :

Persistence of vision of the human eye

Give the meaning of following terms :

Power of accomodation of the human eye

Give me the reason of following terms:

Least distance of distinct vision

Give meaning of the following : 

Range of vision

When Sahil tried to read a book by keeping it at a distance of $25 \mathrm{cm}$, the text print appeared to be blurred. What conclusion can be drawn about the 'least distance of distinct vision' of Sahil's eye?

A person, with a myopic eye, can not see objects beyond $1.2 \mathrm{m}$ distinctly. What can be said about the likely size of his eyeball? State the nature of the corrective lens that is needed to restore his proper vision?