Question

A paper, with two marks having separation d, is held normal to the line of sight of an observer at a distance of 50m. The diameter of the eye-lens of the observer is 2 mm. Which of the following is the least value of d, so that the marks can be seen as separate ? (The mean wavelength of visible light may be taken as 5000 Å)(a) 1.25 m(b) 12.5 cm(c) 1.25 cm(d) 2.5 mm

Answer 1

the answer is b 12.5 centimetre.

Answer 2

Answer:

b 12.5cm

Explanation:

Here Diameter of eye lens is 2mm

Distance is 50m

Angular limit of eyes resolution is q

diameter of eye lens is given by d

Wavelength given here is A=5000 Å=5*$10^{-7}$

Ф=Y/D

λ/d=Y/D

Y=λD/d

since diameter is 2mm=2*$10^{-3}$

Y=5*$10^{-7}$*50/2*$10^{-3}$

Y=12.5*$10^{-3}$meters

Y=12.5 centimeters