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 (UG) 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 n^{th} bright fringe: x_{n} = \frac{nλ D}{d} Position of n^{th} dark fringe: x_{n}^{'} = \frac{( 2 n - 1 ) λ D}{2 d} In air (λ): x_{5, air}^{'} = \frac{( 2 \times 5 - 1 ) λ D}{2 d} = \frac{9 λ D}{2 d} In medium (λ_{m} = λ / μ): x_{8, med} = \frac{8 λ _{m} D}{d} = \frac{8 λ D}{μ d} Given x_{8, med} = x_{5, air}^{'} : \frac{8 λ D}{μ d} = \frac{9 λ D}{2 d} \frac{8}{μ} = \frac{9}{2} μ = \frac{16}{9} \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:

1.59

1.69

1.78

1.25

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