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JEE Main 2025 (24 Jan, Shift 2) · YDSE: Film, Medium & Two Wavelengths

YDSE: Film, Medium & Two Wavelengths question from JEE Main 2025 (24 Jan, Shift 2)

Q25JEE Main 2025 · 24 JAN · SHIFT 2Medium

YDSE: Film, Medium & Two Wavelengths

Young's double slit interference apparatus is immersed in a liquid of refractive index 1.44. It has slit separation of 1.5 mm. The slits are illuminated by a parallel beam of light whose wavelength in air is 690 nm. The fringe-width on a screen placed behind the plane of slits at a distance of 0.72 m, will be:

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Answer: (d)

  1. In liquid β=λDμd\beta = \dfrac{\lambda D}{\mu d}.
  2. β=690×10−9×0.721.44×1.5×10−3=2.3×10−4 m\beta = \dfrac{690\times10^{-9} \times 0.72}{1.44 \times 1.5\times10^{-3}} = 2.3\times10^{-4}\text{ m}
  3. So the answer is (d) 0.23 mm.
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