Question

Two parallel pillars are 11km away from an observer. the minimum distance between the pillars so that they can be seen separately wwilll be -

Answer 1

For the clear veiw  the angular separation of two distant objects at the eye should be = 0.0002 radians or 0.687 ' 

separation = x  

angular separation = x/11000  = 0.0002
x = 2.2 m

minimum angular separation= Ф ≈ 1.22 x λ / D
λ = wavelength of the light rays
D = diameter of the pupil