1. Read the section in your textbook on double slit interference and diffraction (Chapter 36, Section 4). Suppose monochromatic light is incident on a barrier with two slits, as in Fig. 19. Each slit has Width w, and the center-to-center separation of the slits is d. What happens to the number of bright fringes visible Within the central diffraction envelope as d increases and w is xed? What happens to the number of bright fringes visible within the central diffraction envelope as w increases and d is fixed? 2. Read the section in your textbook on diffraction gratings (Chapter 36, Section 5). Suppose monochro- matic light is incident on a diffraction grating. How does the width of a bright fringe observed on a distant screen depend on the number of illuminated slits N? How will the pattern of bright fringes created by the grating be similar to that of a double-slit interference pattern? How will the patterns differ? Second order 02 A First order 01 . B Zeroth order C D E First order F Screen Second order Figure 19: Geometry for double-slit interference