JEE Main 2015 · 4 Apr · Shift 1 · Physics Q26

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PhysicsSingle correct+4 / -1Question 26 of 90

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 that human eye can resolve at 500 nm wavelength is :

1 μm

30 μm

100 μm

300 μm

Answer and worked solution

Official answer: B

$\theta=\frac{1.22\lambda}D=\frac{1.22\times5\times10^{-7}}{5\times10^{-3}}=1.22\times10^{-4}\text{ rad}.$
Separation $=0.25\times1.22\times10^{-4}\approx30\ \mu$ m.

Topics:Resolving power Optical instruments

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JEE Main 2015 · 4 Apr · Shift 1, Physics question 26