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

The least distance of distinct vision for a farsighted person is $1 \ m$. The optical power of the lens of his spectacles,which effectively reduces his least distance of distinct vision $(LDDV)$ to $25 \ cm$,is:

$A$ presbyopic patient has a near point of $30 \, cm$ and a far point of $40 \, cm$. The dioptric power of the corrective lens required for seeing distant objects is: (in $, D$)

$A$ man who cannot see clearly beyond $5 \, m$ wants to see stars clearly. He should use a lens of focal length ....... $m$.

If the distance of the far point for a myopia patient is doubled,the focal length of the lens required to cure it will become

$A$ person cannot see distinctly at a distance less than $1 \, m$. Calculate the power of the lens that he should use to read a book at a distance of $25 \, cm$.