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Question: Answered & Verified by Expert

In standard Young's double-slit experiment, visible light λ350nm750nm 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 μm is placed in front of slit S2. Which among the following wavelengths is missing at point P, which is directly in front of slit S2?(Neglect dispersion of light)


           

PhysicsWave OpticsJEE Main
Options:
  • A 400 nm
  • B 500 nm
  • C 600 nm
  • D 700 nm
Solution:
1164 Upvotes Verified Answer
The correct answer is: 400 nm
Net path difference = μ - 1 t - yd D

=32-16 μm-d/2dD=1 μm

For Destructive interference

Δx=1 μm=2n+1λ2λ=22n+1 μm

λ = 2000 nm 2 + 1 = 2000 3            ( n=1 )

λ=2000 nm4+1=20005nm=400 nm      ( n=2 )

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