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JEE Main 2021 (27 Jul, Shift 2) · YDSE: Film, Medium & Two Wavelengths

YDSE: Film, Medium & Two Wavelengths question from JEE Main 2021 (27 Jul, Shift 2)

Q54JEE Main 2021 · 27 JUL · SHIFT 2Medium

YDSE: Film, Medium & Two Wavelengths

The difference in the number of waves when yellow light propagates through air and vacuum columns of the same thickness is one. The thickness of the air column is ___________ mm. [Refractive index of air = 1.0003, wavelength of yellow light in vacuum = 6000 A˚\text{\AA}]

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

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Answer: 2

  1. Number of waves in thickness tt: air μtλ\frac{\mu t}{\lambda}, vacuum tλ\frac{t}{\lambda}.
  2. (μ−1)tλ=1⇒t=6×10−70.0003=2×10−3\frac{(\mu-1)t}{\lambda} = 1 \Rightarrow t = \frac{6\times10^{-7}}{0.0003} = 2\times10^{-3} m
  3. So the answer is 2 mm.
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