Q. The head lights of a jeep are 1.2 m apart. If the pupil of the eye of an observer has a diameter of 2mm and light of wavelength $5896\ Å$ is used, what should be the maximum distance of the jeep from the observer if the two head lights are just separated?
A) 33.9 km
B) 33.9 m
C) 3.34 km
D) 3.39 m
Explanation
(c) Distance of jeep, $x = \frac{D \times d}{1.22 \times \lambda}$
Where D = diameter of lens
d = separation between sources.
$\Longrightarrow \ x = \frac{(2 \times 10^{- 3}) \times 1.2}{1.22 \times 5896 \times 10^{- 10}}$
$\ = \ 3337\ m$
$\Longrightarrow \ x = 3.34\ km$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.