A telescope has an objective lens of `10cm` diameter and is situated at a distance of one kilometre 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 Å`, of the order of

Options

A. 5 m
B. 5 mm
C. 5 cm
D. 0.5 m

Answer

B

Explanation

`therefore =d/D` but `theta~~lambda/a`
(Note : exact relation `theta=1.22/a lambda`)
`d/D=lambda/a rArr d=(lambdaD)/a`
`rArr d=(5000xx10^(-10) xx10^3)/(10xx10^(-2))`=5mm