Young’s double slit experiment is first performed in air and then in a medium other than air. It is found that 8^th bright fringe in the medium lies w - Physics MCQ NEET 2017 2026 | ExamTest.live

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Young’s double slit experiment is first performed in air and then in a medium other than air. It is found that bright fringe in the medium lies where dark fringe lies in air. The refractive index of the medium is nearly:

Solution & Step-by-step Explanation

Position of 5^{t h} dark fringe in air: y_{d} = (2 \times 5 - 1) \frac{λ D}{2 d} = \frac{9 λ D}{2 d} .Position of 8^{t h} bright fringe in medium: y_{b} = 8 \frac{λ ^{'} D}{d} = 8 \frac{λ D}{μ d} .Equating the positions: \frac{9 λ D}{2 d} = \frac{8 λ D}{μ d} \frac{9}{2} = \frac{8}{μ} ⟹ μ = \frac{16}{9} \approx 1.777 \approx 1.78.

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Young’s double slit experiment is first performed in air and then in a medium other than air. It is found that bright fringe in the medium lies where dark fringe lies in air. The refractive index of the medium is nearly:

1.25

1.59

1.69

1.78

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