The limit to the eye’s acuity is actually related to diffraction by the pupil.
(a) what is the angle between two just-resolvable points of light for a 3.00-mm-diameter pupil, assuming an average wavelength of 550 nm?
(b) take your result to be the practical limit for the eye. what is the greatest possible distance a car can be from you if you can resolve its two headlights, given they are 1.30 m apart?
(c) what is the distance between two just-resolvable points held at an arm’s length (0.800 m) from your eye?
(d) how does your answer to (c) compare to details you normally observe in everyday circumstances?