$A$ man with defective eyes cannot see objects distinctly at a distance of more than $60 \, cm$ from his eyes. The power of the lens to be used will be:

The near point and far point of a person are $40\,cm$ and $250\,cm$ respectively. Determine the power of the lens he/she should use while reading a book kept at a distance of $25\,cm$ from the eye $..........D$

$A$ 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 least distance of distinct vision of a long-sighted person is $60 \ cm$. By using a spectacle lens, this distance is reduced to $12 \ cm$. The power of the lens is

Your friend is having an eyesight problem. She is not able to see a distant uniform window mesh clearly,and it appears to her as non-uniform and distorted. The doctor diagnosed the problem as:

Myopia is a defect of the eye due to which a person experiences difficulty in seeing .......