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JEE Main 2016 (9 Apr, Shift 1) · YDSE: Fringe Width & Fringe Positions

YDSE: Fringe Width & Fringe Positions question from JEE Main 2016 (9 Apr, Shift 1)

Q70JEE Main 2016 · 9 APR · SHIFT 1Difficult

YDSE: Fringe Width & Fringe Positions

In Young’s double slit experiment, the distance between slits and the screen is 1.0 m and monochromatic light of 600 nm is being used. A person standing near the slits is looking at the fringe pattern. When the separation between the slits is varied, the interference pattern disappears for a particular distance d0 between the slits. If the angular resolution of the eye is (160)∘\left(\frac{1}{60}\right)^\circ, the value of d0 is close to:

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Answer: (b)

  1. Fringes vanish for the eye when angular fringe width λd0\frac{\lambda}{d_0} equals the eye's resolution.
  2. (160)∘=π180×60=2.91×10−4\left(\frac{1}{60}\right)^\circ = \frac{\pi}{180\times60} = 2.91\times10^{-4} rad
  3. d0=600×10−92.91×10−4≈2.06×10−3d_0 = \frac{600\times10^{-9}}{2.91\times10^{-4}} \approx 2.06\times10^{-3} m
  4. So the answer is (b) 2 mm.
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