---
title: "Monochromatic light is incident normally on a single narrow slit of width \\(a\\), forming a diffraction pattern on a screen located a distance \\(L\\) away, where \\(L \\gg a\\). The experiment is performed first with red light (\\(\\lambda_{\\text{red}} \\approx 700 \\text{ nm}\\)) and then with blue light (\\(\\lambda_{\\text{blue}} \\approx 450 \\text{ nm}\\)). Which row in the table correctly compares the central maximum width for red light (\\(w_{\\text{red}}\\)) and blue light (\\(w_{\\text{blue}}\\)), and states the ratio of the central maximum width to the width of a secondary maximum (\\(w_{\\text{central}} / w_{\\text{secondary}}\\)) for either wavelength?  | Row | Central Maximum Width Comparison | Ratio \\(w_{\\text{central}} / w_{\\text{secondary}}\\) | | :— | :— | :— | | A | \\(w_{\\text{red}}  w_{\\text{blue}}\\) | \\(2\\) | | C | \\(w_{\\text{red}} > w_{\\text{blue}}\\) | \\(1\\) | | D | \\(w_{\\text{red}} < w_{\\text{blue}}\\) | \\(2\\) |"
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url: "https://nerd-notes.com/ubq/117402/"
date_modified: "2026-08-04T06:52:04+00:00"
---

# Monochromatic light is incident normally on a single narrow slit of width \(a\), forming a diffraction pattern on a screen located a distance \(L\) away, where \(L \gg a\). The experiment is performed first with red light (\(\lambda_{\text{red}} \approx 700 \text{ nm}\)) and then with blue light (\(\lambda_{\text{blue}} \approx 450 \text{ nm}\)). Which row in the table correctly compares the central maximum width for red light (\(w_{\text{red}}\)) and blue light (\(w_{\text{blue}}\)), and states the ratio of the central maximum width to the width of a secondary maximum (\(w_{\text{central}} / w_{\text{secondary}}\)) for either wavelength?

| Row | Central Maximum Width Comparison | Ratio \(w_{\text{central}} / w_{\text{secondary}}\) |
| :— | :— | :— |
| A | \(w_{\text{red}}  w_{\text{blue}}\) | \(2\) |
| C | \(w_{\text{red}} > w_{\text{blue}}\) | \(1\) |
| D | \(w_{\text{red}} < w_{\text{blue}}\) | \(2\) |

Monochromatic light is incident normally on a single narrow slit of width \(a\), forming a diffraction pattern on a screen located a distance \(L\) away, where \(L \gg a\). The experiment is performed first with red light (\(\lambda_{\text{red}} \approx 700 \text{ nm}\)) and then with blue light (\(\lambda_{\text{blue}} \approx 450 \text{ nm}\)). Which row in the table correctly compares the central maximum width for red light (\(w_{\text{red}}\)) and blue light (\(w_{\text{blue}}\)), and states the ratio of the central maximum width to the width of a secondary maximum (\(w_{\text{central}} / w_{\text{secondary}}\)) for either wavelength?

| Row | Central Maximum Width Comparison | Ratio \(w_{\text{central}} / w_{\text{secondary}}\) |
| :--- | :--- | :--- |
| A | \(w_{\text{red}} < w_{\text{blue}}\) | \(1\) |
| B | \(w_{\text{red}} > w_{\text{blue}}\) | \(2\) |
| C | \(w_{\text{red}} > w_{\text{blue}}\) | \(1\) |
| D | \(w_{\text{red}} < w_{\text{blue}}\) | \(2\) |

![A horizontal schematic of a single-slit diffraction setup. On the left, five parallel horizontal arrows pointing right represent incoming plane waves of light. A vertical barrier with a single central aperture of width labeled a sits in the middle. Rays of light spread outward in a fan shape from the aperture toward a vertical screen located a distance L to the right. On the vertical screen, a graph-like curve aligned vertically shows the diffraction intensity pattern with a wide, tall central peak centered on the central axis, flanked on both top and bottom by significantly smaller, narrower secondary peaks. The distance from the slit barrier to the screen is labeled L. No other labels, lines, text, or axes appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1785826323-Lwl9gT.jpg)

- **A.** Row A
- **B.** Row B
- **C.** Row C
- **D.** Row D

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/117402/*