Question

An astronaut is looking down on earth’s surface from a space shuttle at an altitude of 400 km. Assuming that the astronaut’s pupil diameter is 5 mm and the wavelength of visible light is 500 nm, the astronaut will be able to resolve linear objects of the size of about

• A. 0.5 m
• B. 5 m
• C. 50 m
• D. 500 m

Answer 1

The correct option is C

50 m

$x=\frac{1.22\lambda d}{D}$

$=\frac{1.22\times 500\times {10}^{-9}\times 400\times {10}^3}{5\times {10}^{-3}}$

$=48.8m$