In Young's double slit experiment, the two slits are 'd' distance apart. Interference pattern is observed on a screen at a distance ' D ' from the slits. A dark fringe is obse

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In Young's double slit experiment, the two slits are 'd' distance apart. Interference pattern is observed on a screen at a distance ' D ' from the slits. A dark fringe is observed on a screen directly opposite to one of the slits. The wavelength of light is

TestHub · Accepted Answer

S 2 ​ P ​ = ( D 2 + d 2 ) 1/2 = D [ 1 + D 2 d 2 ​ ] 1/2 ​ Using binomial equation, S 2 ​ P = D [ 1 + 2 1 ​ D 2 d 2 ​ ] 1/2 = D + 2 D d 2 ​ ⇒ Path difference = 2 D d 2 ​ For dark fringe, 2 D d 2 ​ = 2 λ ​ ∴ λ = D d 2 ​

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