1. Fig. 38-7 Phasor diagrams used to find the amplitude of the E field in single-slit diffraction. (a) All phasors are in phase. (b) Each phasor differs in phase slightly from the preceding one. (c) Limit reached when the slit is subdivided into infinitely many strips.

2. Fig. 38-8 (a) Intensity distribution for a single slit. (b) Photograph of the Fraunhofer diffraction pattern of a single horizontal slit.

3. Fig. 38-9 (a) When the slit width a is less than or equal to the wavelength, the central maximum is spread out. (b), (c) The angular width of the central maximum decreases when the ratio of a / is increased.

4. Fig. 38-10 (a) Single-slit pattern for a slit of width a. (b) Double-slit interference pattern for narrow slits. (c) Calculated pattern for curve in b. Intensity as function of  is shown in red. <<< narrow separation d = 4a

5. Fig. 38-11 In multiple-slit diffraction, rays from every slit arrive in phase if the path difference between adjacent slits is a whole number of wavelengths. n = d sin  = n

6. Fig. 38-12 Phasor diagrams for light passing through 8 narrow slits. Intensity maxima occur when the phase difference  = 0, 2 , 4 , … There are 7 minima. Phasor diagrams are shown for: (a)  =  (b)  =  (c)  = 