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Question: Answered & Verified by Expert
In a Young's double slit experiment, a laser light of 560 nm produces an interference pattern with consecutive bright fringes' separation of 7.2 mm. Now another light is used to produce an interference pattern with consecutive bright fringes' separation of 8.1 mm. The wavelength of second light is _____ nm.
PhysicsWave OpticsJEE MainJEE Main 2022 (28 Jul Shift 1)
Solution:
1610 Upvotes Verified Answer
The correct answer is: 630

Given here: λ1=560×10-9 mβ1=7.2×10-3 m and β2=8.1×10-3 m.

Let d be the width and D be the distance between slit and screen then fringe width, β=λDd.

Thus, from above,  βλ

So, the wavelength of second light is λ2=β2β1λ1=98λ1

   λ2=98×560=630 nm.

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