NTA Abhyas JEE Main2020PhysicsWave OpticsPractice
In standard Young's double-slit experiment, visible light λ ∈ 350 nm ,  750 nm is used in both the slits. Distance between the slits is 2   mm , and the distance of the screen from the slits is 1   m . A thin glass slab μ = 1.5 of thickness 6   μ m is placed in front of slit S 2 . Which among the following wavelengths is missing at point P, which is directly in front of sl
Options
- A400 nm
- B500 nm
- C600   nm
- D700   nm
Correct answer
A. 400 nm
Step-by-step solution
Net path difference = μ - 1 t - yd D = 3 2 - 1 6 μ m - d / 2 d D = 1 μ m For Destructive interference Δ x = 1 μ m = 2 n + 1 λ 2 ⇒ λ = 2 2 n + 1 μ m λ = 2000 nm 2 + 1 = 2000 3 ( n = 1 ) λ = 2000 nm 4 + 1 = 2000 5 nm = 400 nm ( n = 2 )