The two headlights of an approaching automobile are 1.42 m apart. We have to find (a) angular separation and (b) the maximum distance at which the eye can resolve them. We may assume a pupil diameter of 5.00 mm and a wavelength of 562 nm. Also, we will assume that diffraction effects alone limit the resolution.
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Solution: Click For PDF Version (a)
We will use
Rayleigh’s criterion that two objects must have an angular
separation at least
Data of the problem are
Therefore,
(b) The maximum distance at which the headlights separated by a distance of 1.42 m will be barely resolvable will therefore be
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to be resolvable by a lens of aperture d
using light of wavelength
.
