Assuming human pupil to have a radius of 0.25 cm and a comfortable viewing distance of 25 cm, the minimum separation between two objects than human eye can resolve at 500nm wavelength is :

Options

A. `1mu m`
B. `30 mu m`
C. `100 mu m`
D. `300 mu m`

Answer

B

Explanation

Limit of resolution, `d = (1.22 lambda)/(2 mu sin theta)`

Now, `theta = (arc)/(radius) ~~ sin theta = (0.25)/(25) = (1)/(100)`
`:. d = (1.22 xx 500 xx 10^(-9))/(2 xx 1 xx ((1)/(100)))`
`:. d = 3.05 xx 10^(-5)m = 30.5 mu m ~~ 30 mu m`