In a double-slit interference experiment using light of wavelength 600 nm, the slits are separated by 0.20 mm and the screen is placed 1.5 m away. What is the distance between consecutive bright fringes on the screen?
Answer and explanation
Correct answer: B. 4.5 mm
- Step 1: Recall fringe spacing formula: Delta y = (lambda * D) / d.
- Step 2: Convert units to meters: lambda = 600 10^(-9) m; D = 1.5 m; d = 0.20 10^(-3) m.
- Step 3: Compute: Delta y = (600 10^(-9) 1.5) / (0.20 10^(-3)) = (900 10^(-9)) / (2.0 10^(-4)) = 4.5 10^(-3) m = 4.5 mm.
Answer
4.5 mm.
Why not the others: '2.25 mm' halves the distance to the screen; '9.0 mm' doubles the wavelength; '0.45 mm' makes a unit conversion error.
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