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A double-slit arrangement produces interference fringes for sodium light (λ = 589 nm) that are 0.20° apart. What is the angular fringe separation if the entire arrangement is immersed in water

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प्रश्न

A double-slit arrangement produces interference fringes for sodium light (λ = 589 nm) that are 0.20° apart. What is the angular fringe separation if the entire arrangement is immersed in water (n = 1.33)?

संख्यात्मक
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उत्तर

Given: θ1 = 0.20°, nw = 1.33

In the first approximation,

D sin θ1 = yand D sin θ2 = y2

`therefore (sin theta_2)/(sin theta_1) = "y"_2/"y"_1`   ...(1)

Now, `y prop (lambdaD)/d`

For given d and D,

y ∝ λ

∴ `y_2/y_1 = lambda_2/lambda_1`    ...(2)

Now, `n_w = lambda_1/lambda_2`    ...(3)

From Eqs. (1), (2) and (3), we get

`(sin theta_2)/(sin theta_1) = lambda_2/lambda_1 = 1/n_w`

∴ `sin theta_2 = sin theta_1/n_w`

`sin theta_2 = (sin 0.2)/1.33`

`sin theta_2 = 0.0035/1.33`

sinθ2 =  0.0026

θ2 = sin−1 0.0026 

θ2 = 9'

θ2 = 0.15°

This is the required angular fringe separation.

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पाठ 7: Wave Optics - Exercises [पृष्ठ १८५]

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बालभारती Physics [English] Standard 12 Maharashtra State Board
पाठ 7 Wave Optics
Exercises | Q 15. | पृष्ठ १८५

संबंधित प्रश्‍न

The intensity at the central maximum (O) in a Young’s double slit experimental set-up shown in the figure is IO. If the distance OP equals one-third of the fringe width of the pattern, show that the intensity at point P, would equal `(I_0)/4`.


Answer the following question.
Describe any two characteristic features which distinguish between interference and diffraction phenomena. Derive the expression for the intensity at a point of the interference pattern in Young's double-slit experiment.


Answer in brief:

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