Chapter 35

1. Chapter 35 Interference (cont.)

2. Figure 35.11 (right) shows why thin-film interference occurs, with an illustration. • Figure 35.12 (below) shows interference of an air wedge. Interference in thin films

3. Follow the text analysis of thin-film interference and phase shifts during reflection. Use Figure 35.13 below. Phase shifts during reflection

4. Q35.6 An air wedge separates two glass plates as shown. Light of wavelength l strikes the upper plate at normal incidence. At a point where the air wedge has thickness t, you will see a bright fringe if t equals l/2. 3l/4. C. . D. either A. or C. E. any of A., B., or C.

5. A35.6 An air wedge separates two glass plates as shown. Light of wavelength l strikes the upper plate at normal incidence. At a point where the air wedge has thickness t, you will see a bright fringe if t equals l/2. 3l/4. C. . D. either A. or C. E. any of A., B., or C.

6. Figure 35.16 below illustrates the interference rings (called Newton’s rings) resulting from an air film under a lens. Newton’s rings

7. The lens to be tested is placed on top of the master lens. If the two surfaces do not match, Newton’s rings will appear, as in Figure 35.17 at the right. Using interference fringes to test a lens

8. Chapter 36 Diffraction

9. According to geometric optics, a light source shining on an object in front of a screen should cast a sharp shadow. Surprisingly, this does not occur because of diffraction. Diffraction

10. Fresnel diffraction: Source, screen, and obstacle are close together. • Fraunhofer diffraction: Source, screen, and obstacle are far apart. • Figure 36.2 below shows the diffraction pattern of a razor blade. Diffraction and Huygen’s Principle

11. In Figure 36.3 below, the prediction of geometric optics in (a) does not occur. Instead, a diffraction pattern is produced, as in (b). Diffraction from a single slit

12. Figure 36.4 below shows Fresnel (near-field) and Frauenhofer (far-field) diffraction for a single slit. Fresnel and Fraunhofer diffraction by a single slit

13. Figure 36.5 below shows the geometry for Fraunhofer diffraction. Locating the dark fringes

14. Figure 36.6 (bottom left) is a photograph of a Fraunhofer pattern of a single horizontal slit. An example of single-slit diffraction

15. Figure 36.9 at the right shows the intensity versus angle in a single-slit diffraction pattern. • Part (b) is photograph of the diffraction of water waves. Intensity maxima in a single-slit pattern

16. The single-slit diffraction pattern depends on the ratio of the slit width a to the wavelength . (Figure 36.10 below.) Width of the single-slit pattern

17. Q36.1 Light of wavelength l passes through a single slit of width a. The diffraction pattern is observed on a screen that is very far from from the slit. Which of the following will give the greatest increase in the angular width of the central diffraction maximum? A. Double the slit width a and double the wavelength l. B. Double the slit width a and halve the wavelength l. C. Halve the slit width a and double the wavelength l. D. Halve the slit width a and halve the wavelength l.

18. A36.1 Light of wavelength l passes through a single slit of width a. The diffraction pattern is observed on a screen that is very far from from the slit. Which of the following will give the greatest increase in the angular width of the central diffraction maximum? A. Double the slit width a and double the wavelength l. B. Double the slit width a and halve the wavelength l. C. Halve the slit width a and double the wavelength l. D. Halve the slit width a and halve the wavelength l.

19. Q36.2 In a single-slit diffraction experiment with waves of wavelength l, there will be no intensity minima (that is, no dark fringes) if the slit width is small enough. What is the maximum slit width a for which this occurs? A. a = l/2 B. a = l C. a = 2l D. The answer depends on the distance from the slit to the screen on which the diffraction pattern is viewed.

20. A36.2 In a single-slit diffraction experiment with waves of wavelength l, there will be no intensity minima (that is, no dark fringes) if the slit width is small enough. What is the maximum slit width a for which this occurs? A. a = l/2 B. a = l C. a = 2l D. The answer depends on the distance from the slit to the screen on which the diffraction pattern is viewed.

21. For slits extremely narrow, behaves very close to ideal case from previous chapter • For wider slits, behaves like a combination of single-slit diffraction and double-slit interference. Two slits of finite width

22. Figure 36.15 below shows the interference pattern for 2, 8, and 16 equally spaced narrow slits. Interference pattern of several slits

23. Q36.3 In Young’s experiment, coherent light passing through two slits separated by a distance d produces a pattern of dark and bright areas on a distant screen. If instead you use 10 slits, each the same distance d from its neighbor, how does the pattern change? A. The bright areas move farther apart. B. The bright areas move closer together. C. The spacing between bright areas remains the same, but the bright areas become narrower. D. The spacing between bright areas remains the same, but the bright areas become broader.

24. A36.3 In Young’s experiment, coherent light passing through two slits separated by a distance d produces a pattern of dark and bright areas on a distant screen. If instead you use 10 slits, each the same distance d from its neighbor, how does the pattern change? A. The bright areas move farther apart. B. The bright areas move closer together. C. The spacing between bright areas remains the same, but the bright areas become narrower. D. The spacing between bright areas remains the same, but the bright areas become broader.