Electromagnetic Waves and Wave Optics: Path Difference — Geometry MCQ

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Path Difference — GeometryHardQuestion 20212

Question

In YDSE with slit separation d = 1 mm and screen at D = 1 m, the 3rd bright fringe is at distance y from centre for λ = 500 nm. y equals:

1.5 mm

y_n = nλD/d = 3 × 500×10⁻⁹ × 1/(10⁻³) = 3 × 500×10⁻⁶ = 1500×10⁻⁶ = 1.5 mm.