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Question:

Calculate the limit of resolution of a telescope objective having a diameter of 200 cm, if it has to detect light of wavelength 500 nm coming from a star

305 × 10^-9 radian

152.5 × 10^-9 radian

457.5 × 10^-9 radian

610 × 10^-9 radian

Solution:

Correct option is A. 305 × 10^-9 radian
Limit of resolution of telescope = 1.22 λ/D
θ = 1.22 × 500 × 10^-9 / 200 × 10^-2 = 305 × 10^-9 radian