question_answer

            Diameter of human eye lens is 2 mm. What will be the minimum distance between two points to resolve them, which are situated at a distance of 50 m from eye? The wavelength of light is \[5000\text{ }{\AA}\]:                             [AIPMT 2002]

A)              2.32 m  

B)                   4.28 mm

C)                   1.25 cm 

D)                    12.48 cm

Correct Answer: C

Solution :

Key Idea: Angular limit of resolution of eye is the ratio of wavelength of light to diameter of eye lens.

Angular limit of resolution of eye

i.e.,                                              (i)

If y is the minimum resolution between two objects at distance D from eye, then

(ii)

From Eqs. (i) and (ii), we have

or                                             (iii)

Given,

Substituting in Eq. (iii), we get