99 Percentile Qs Bank for JEE MainPhysicsWave Optics
In Young's double-slit experiment, in an interference pattern, the second minimum is observed exactly in front of one slit. The distance between the slits is d and the distance between source and screen is D . The wavelength of the light source used is
Options
- Ad 2 D
- Bd 2 2 D
- Cd 2 3 D
- Dd 2 4 D
Correct answer
C. d 2 3 D
Step-by-step solution
Distance of second minima from central point is y = d 2 . We know that minima is given by, dsinθ =   n - 1 2 λ dy D =   2 - 1 2 λ d   2 = D d 2 × 2 - 1 2 λ ∴ d 2 = D d × 3 2 λ ∴ λ = d 2 3 D