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QJEEM20Ph8bad: JEE Main 2020 Physics - Class 12 JEEM20Ph8bad Solution: Interference fringes are observed on a screen by illuminating…

Interference fringes are observed on a screen by illuminating two thin slits 1 mm apart with a light source ( λ\lambda = 632.8 nm). The distance between the screen and the slits is 100 cm. If a bright fringe is observed on a screen at a distance of 1.27 mm from the central bright fringe, then the path difference between the waves, which are reaching this point from the slits is close is

Multiple Choice Options

  • A 1.27 μ\mu m
  • B 2.05 μ\mu m
  • C 2.87 nm
  • D 2 nm

Step-by-Step Verified Solution

JEE Main 2020 (Online) 2nd September Morning Slot Physics - Wave Optics Question 94 English Explanation
y = nDλd{{nD\lambda } \over d}

⇒\Rightarrow n = ydDλ{{yd} \over {D\lambda }}

= 1.27×10−3×10−31×632.8×10−9{{1.27 \times {{10}^{ - 3}} \times {{10}^{ - 3}}} \over {1 \times 632.8 \times {{10}^{ - 9}}}} = 2

Path difference Δ\Delta x = n λ\lambda

= 2 ×\times 632.8 nm

= 1265.6 nm

= 1.27 μ\mu m

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