8.2.2—Experiments that demonstrate diffraction including the qualitative effect of

In a diffraction experiment, observe the angular spread or fringe pattern while varying slit width or wavelength; larger λ or smaller slit gives more spreading.

Keep source, detector and geometry controlled, and compare the pattern qualitatively unless a quantitative model is required.

A laser through a narrower slit produces a wider central maximum than through a wider slit, while colour-dependent wavelength changes the spread.

A wider central maximum does not mean the waves travelled faster; it reflects the geometry-to-wavelength ratio.