A mixture of Yellow light of wavelength 580 nm and blue light of wave length 450 nm is incident normally on an air film of thickness 2.9 10⁻⁴ ~mm . The colour of reflected light is

Step-by-step solution

Using the bragg's law the path difference for first reflected light, The thickness of film is d = 2 . 9 × 10 - 4   mm The angle between the incident ray and film is 90 ° Therefore, n λ = 2 d sin θ λ = 2 d sin θ = 2 × 2 . 9 × 10 - 4   mm × sin 90 ° λ = 5 . 8 × 10 - 7   m = 580   nm The wavelength obtained is corresponding to Yellow light. Thus, the colour of reflected light is, Yellow.