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← JEE Main 2022 · 27 Jun · Shift 1
PhysicsInteger+4 / -1Question 53 of 90

JEE Main 2022 · 27 Jun · Shift 1, Physics question 53

In Young's double slit experiment the two slits are 0.6 mm distance apart. Interference pattern is observed on a screen at a distance 80 cm from the slits. The first dark fringe is observed on the screen directly opposite to one of the slits. The wavelength of light will be ______ nm.

Answer and worked solution

Official answer: 450

First dark fringe at y=λD2dy=\dfrac{\lambda D}{2d}; opposite a slit, y=d2y=\frac d2.

So λ=d2D=(0.6×10−3)20.8=4.5×10−7\lambda=\dfrac{d^2}D=\dfrac{(0.6\times10^{-3})^2}{0.8}=4.5\times10^{-7} m =450=450 nm.

Answer: 450