JEE Main 2019PhysicsWave OpticsEasyMCQ

JEE Main 2019 — Wave Optics Question with Solution

JEE Main 2019 (10 Jan Shift 1)

Question

In a Young's double slit experiment slit separation 0.1 mm, one observes a bright fringe at angle 140 rad by using light of wavelength λ1. When the light of wavelength λ2 is used a bright fringe is seen at the same angle in the same set up. Given that λ1 and λ2 are in visible range 380 nm to 740 nm, their values are:

Choose an option

Show full solutionCorrect option: C
Correct answer
C625 nm, 500 nm

Step-by-step explanation

d sinθ=nλ

∴λ=dsinθn=10-4×140×1n

∴λ=2.5×10-6n=2500×10-9n=2500nnm

Putting n=1, λ1=2500 nm

n=2, λ2=1250 nm

n=3, λ3=833 nm

n=4, λ4=625 nm

n=5, λ5=500 nm

n=6, λ6=357 nm

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About this question

This is a previous-year question from JEE Main 2019, covering the Wave Optics chapter of Physics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.