In Young's double slit experiment, in an interference pattern, a minimum is observed exactly in front of one slit. The distance between the two coherent sources is d and D is the distance between source and screen. The possible wavelengths used are proportional to

Step-by-step solution

The distance between the coherent sources is d and the distance to the screen is D . For a point at position y = d/2 directly in front of one slit, the path difference becomes x = (d/2)d D = d^2 2D . Destructive interference requires x = (2n - 1) 2 for n = 1, 2, 3, . Equating the expressions gives d^2 2D = (2n - 1) 2 . Simplifying yields = d^2 (2n - 1)D . The possible wavelengths are therefore proportional to 1 D , 1 3D , 1 5D , … matching the sequence in option B. Final answer: B