A myopic adult has a far point at `0.1 m`. His power of accomodation is `4` diopters.
(i) What power lenses are required to see distant objects ?
(ii) What is his near point without glasses ?
(iii) What is his near point with glasses ? (Take the image distance from the lens of the eye to the retina to be 2 cm).

Options

A. 25m
B. 0.25 m
C. 2.5 m
D. 20 m

Answer

2

Explanation

With glasses `P_(n)=P_(f)+4`=54
54=`1/x_(n) + 1/0.02 = 1/x_(n) + 50`
`1/x_(n) = 4 implies x_(n) = 1/4 m = 0.25m`