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Question: Answered & Verified by Expert
In Young's experiment, the distance between slits is $0.28 \mathrm{~mm}$ and distance between slits and screen is 1.4 $\mathrm{m}$. Distance between central bright fringe and third bright fringe is $0.9 \mathrm{~cm}$. What is the wavelength of used light
PhysicsWave OpticsJEE Main
Options:
  • A $5000 Å Å$
  • B $6000 Å$
  • C $7000 Å$
  • D $9000 Å$
Solution:
2539 Upvotes Verified Answer
The correct answer is: $6000 Å$
Position of $3^{\text {rd }}$ bright fringe $x_3=\frac{3 D \lambda}{d}$
$\Rightarrow \lambda=\frac{x_3 d}{3 D}=\frac{\left(0.9 \times 10^{-2}\right) \times\left(0.28 \times 10^{-3}\right)}{3 \times 1.4}=6000 Å$

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