BITSAT 2012 Paper

The angular fringe width is given by α =

λ

d

where λ is wavelength and d is the distance between two coherent sources. Thus
d =

λ

α

Given, λ = 6280 Å , α = 1° =

π

180

radian.
Thus d =

6280×10−10

3.14

× 180
= 3.6 × 10–5 m = 0.036 mm