JEE MAIN - Physics (2019 - 8th April Evening Slot - No. 26)

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 :-
610 × 10–9 radian
457.5 × 10–9 radian
305 × 10–9 radian
152.5 × 10–9 radian

Explanation

Limit of resolution of telescope $$(\theta) = {{1.22\lambda } \over D}$$

$$\theta = {{1.22 \times 500 \times {{10}^{ - 9}}} \over {200 \times {{10}^{ - 2}}}} = {{1.22 \times 500 \times {{10}^{ - 9}}} \over 2}$$

$$\theta $$ = 305 × 10–9 radian

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