Ray Optics And Optical Instruments Ques 72
72. A telescope has an objective lens of $10$ $ cm$ diameter and is situated at a distance of one kilometer from two objects. The minimum distance between these two objects, which can be resolved by the telescope, when the mean wavelength of light is $5000 $ $\AA$, is of the order of
[2004]
(a) $5 $ $cm$
(b) $0.5$ $m$
(c) $5 $ $m$
(d) $5$ $ mm$
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Answer:
Correct Answer: 72.(d)
Solution:
- (d) Here, $\frac{x}{1000}=\frac{1.22 \lambda}{D}$
or, $x=\frac{1.22 \times 5 \times 10^{3} \times 10^{-10} \times 10^{3}}{10 \times 10^{-2}}$
or, $x=1.22 \times 5 \times 10^{-3} m=6.1$ $ mm$
$\therefore x$ is of the order of $5 $ $mm$.
BETA
