The human eye has a lens which has a

$A$ person can see objects clearly when they lie between $40 \ cm$ and $400 \ cm$ from his eye. In order to increase the maximum distance of distant vision to infinity, the type of lens and power of the correction lens required respectively are

The image formed on the retina of the eye is proportional to:

The light when enters the human eye experiences most of the refraction while passing through

Calculate the focal length of a reading glass of a person if his distance of distinct vision is $ 75 \ cm $. (in $cm$)

$A$ short-sighted person can see distinctly only those objects which lie between $10\, cm$ and $100\, cm$ from him. The power of the spectacle lens required to see a distant object is