A teacher wishes to demonstrate how the sharpness of a shadow cast by white light depends on both the width of an aperture and the color components of the light. Three interchangeable single slits are provided with widths 0.050mm, 0.10mm, and 1.0mm. The screen is fixed 1.5m from the slit. The experiment will be repeated in air and then with the entire apparatus submerged in water (refractive index n=1.33).
(a) Outline a procedure, including any measurements, that would allow students to observe how the diffraction pattern changes as different slit widths are used.
(b) Predict qualitatively how the width of the central bright region will differ for red and blue components of the white light for each slit. Rank the three slit widths from "most pronounced color spreading" to "least pronounced" and justify your ranking.
(c) Provide a conceptual explanation, without numerical calculation, linking your predictions in part (b) to the relationship between slit width and wavelength.
(d) Describe how immersing the apparatus in water is expected to alter the observed patterns. Explain in terms of the wavelength change of light in the medium and any consequent effect on diffraction.