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Wave Optics — Physics STD 12 Science — Question

Maharashtra BoardEnglish MediumSTD 12 SciencePhysicsWave Optics3 Marks
Question
The optical path difference between identical waves from two coherent sources and arriving at a point is $87 \lambda$. What can you say about the resultant intensity at the point? If the path difference is $49.19 \mu m$, calculate the wavelength of light.
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Answer

Data : Path difference $=87 \lambda=49.19 / rm$.
(i) Path difference $=87 \lambda=n \lambda$, where $n=87$. As the path difference is an integral multiple of the wavelength $\lambda$, the point where the waves interfere is a bright point with maximum intensity-
(ii) $87 \lambda=49.19 \mu n =49.19 \times 10^{6 f } m$.
$
\therefore \lambda=\frac{49.19 \times 10^{-4}}{87}=5.654 \times 10^7 m =5654 A
$

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