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JEE Main 2022 (27 Jun, Shift 1) · YDSE: Film, Medium & Two Wavelengths

YDSE: Film, Medium & Two Wavelengths question from JEE Main 2022 (27 Jun, Shift 1)

Q52JEE Main 2022 · 27 JUN · SHIFT 1Medium

YDSE: Film, Medium & Two Wavelengths

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.

Numerical answer type. Work it out, then open the answer.

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Answer: 450

  1. First dark fringe opposite a slit: d22D=λ2⇒λ=d2D\dfrac{d^2}{2D} = \dfrac{\lambda}{2} \Rightarrow \lambda = \dfrac{d^2}{D}.
  2. λ=(0.6×10−3)20.8=4.5×10−7 m\lambda = \dfrac{(0.6\times10^{-3})^2}{0.8} = 4.5\times10^{-7}\text{ m}
  3. So λ=450\lambda = 450 nm.
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