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Question
A point is situated at 7cm and 7·2 cm from two coherent sources. Find the· nature of illumination at the point if wavelength of light is 4000A.
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Solution
Path difference = 7.2 cm – 7 cm = 0.2 cm
`"Path diffrence "/lambda=0.2/(4000xx10^-8)=5000`
path difference is integral multiple ofλ
∴ It is bright point
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