NEET2013PhysicsWave OpticsActual
In Young's double slit experiment, the slits are 2 ~mm apart and are illuminated by photons of two wavelengths ₁=12000 Å and ₂=10000 Å . At what minimum distance from the common central bright fringe on the screen 2 ~m from the slit will a bright fringe from one interference pattern coincide with a bright fringe from the other?
Options
- A8 ~mm
- B6 ~mm
- C4 ~mm
- D3 ~mm
Correct answer
B. 6 ~mm
Step-by-step solution
Given ₁=12000 Å and ₂=10000 Å , D=2 ~cm and d=2 ~mm =2 10⁻³ ~cm . We have ₁ ₂ = h₂ h₁ = 12000 10000 = 6 5 as x= u₁ ₁ D d = 5 12000 10⁻¹⁰ 2 2 10⁻³ =5 1.2 10^4 10⁻¹⁰ 10^3=6 ~mm