Question:
In a double-slit experiment using the light of wavelength 600 nm, the angular width of a fringe formed on a distant screen is 0.1°. What is the spacing between the two slits?
Solution:
Wavelength of the light, λ = 600 nm
The angular width of the fringe formed, θ= 0.10 = 0.1 π/180
Spacing between the slits, d = λ/θ = (600 x 10-9 x 180)/(0.1 x 3.14)
= 108000 x 10-9/0.314
d =3.44 x 10-4 m