In double-slit experiment using light of wavelength 600 nm, the angular width of a fringe formed on a distant screen is 0.1º. What is the spacing between the two slits?

Wavelength of light used, λ = 6000 nm = 600 x 10^-9 m

Angular width of fringe, 0 = 0.1° = 0.1 x π/180 = 3.14 /1800 rad

Angular width of a fringe is related to slit spacing (d) as: 0 = λ /d  => d = λ/0

=> d = (600 x 10^-9) /(3.14/1800)  = 3.44 x 10⁻⁴ m

Therefore, the spacing between the slits is 3.44 x 10⁻⁴ m.