Physics

Physics

Problem

Three separate double-slit experiments are conducted using the parameters below. Experiment A: λ=500 nm\lambda = 500\,\text{nm}, d=0.25 mmd = 0.25\,\text{mm}, L=1.0 mL = 1.0\,\text{m} Experiment B: λ=650 nm\lambda = 650\,\text{nm}, d=0.25 mmd = 0.25\,\text{mm}, L=0.50 mL = 0.50\,\text{m} Experiment C: λ=500 nm\lambda = 500\,\text{nm}, d=0.50 mmd = 0.50\,\text{mm}, L=1.0 mL = 1.0\,\text{m} Rank the experiments from largest to smallest spacing between adjacent bright fringes on the screen. Justify your ranking briefly.
Intuitive explanation

The fringe spacing in a double-slit pattern depends on the ratio Δy=λLd\Delta y = \frac{\lambda L}{d}—wavelength and distance to screen push fringes apart, while slit separation squeezes them together. To rank the experiments, calculate this ratio for each: larger λ\lambda and LL increase spacing, larger dd decreases it. Think of it as a competition between diffraction (spreading) and interference geometry (compression).

Intuitive explanation

The fringe spacing in a double-slit pattern depends on the ratio Δy=λLd\Delta y = \frac{\lambda L}{d}—wavelength and distance to screen push fringes apart, while slit separation squeezes them together. To rank the experiments, calculate this ratio for each: larger λ\lambda and LL increase spacing, larger dd decreases it. Think of it as a competition between diffraction (spreading) and interference geometry (compression).

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