In a double-slit experiment, at a certain point on the screen the path difference between the two interfering waves is th of a wavelength. The ratio of the intensity of light at that point to that at the centre of a bright fringe is :

Engineering

Physics

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Question

In a double-slit experiment, at a certain point on the screen the path difference between the two interfering waves is $\frac{1}{8}$ th of a wavelength. The ratio of the intensity of light at that point to that at the centre of a bright fringe is :

0.568

0.672

0.853

0.760

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$I = I_{0} \cos^{2} (\frac{Δϕ}{2})$

$\frac{I}{I_{0}} = \cos^{2} [\frac{\frac{2 π}{λ} \times Δx}{2}] = \cos^{2} (\frac{π}{8}); \frac{I}{I_{0}} = 0 .853$