Find the ratio of the width of the slits to the separation between them, if the first minimum of the single slit pattern falls on the fifth maximum of the double slit pattern. However, when rays travel at an angle, at what angle is the second-order minimum? (b) What is the angle of the third-order minimum? (c) Is there a fourth-order minimum? (d) Use your answers to illustrate how the angular width of the central maximum is about twice the angular width of the next maximum (which is the angle between the first and second minima).ġ2: A double slit produces a diffraction pattern that is a combination of single and double slit interference. When they travel straight ahead, as in Figure 2(a), they remain in phase, and a central maximum is obtained. (Each ray is perpendicular to the wavefront of a wavelet.) Assuming the screen is very far away compared with the size of the slit, rays heading toward a common destination are nearly parallel. These are like rays that start out in phase and head in all directions. According to Huygens’s principle, every part of the wavefront in the slit emits wavelets. Here we consider light coming from different parts of the same slit. The analysis of single slit diffraction is illustrated in Figure 2. (b) The drawing shows the bright central maximum and dimmer and thinner maxima on either side. The central maximum is six times higher than shown. Monochromatic light passing through a single slit has a central maximum and many smaller and dimmer maxima on either side. In contrast, a diffraction grating produces evenly spaced lines that dim slowly on either side of center. Note that the central maximum is larger than those on either side, and that the intensity decreases rapidly on either side. Figure 1 shows a single slit diffraction pattern. Light passing through a single slit forms a diffraction pattern somewhat different from those formed by double slits or diffraction gratings. Discuss the single slit diffraction pattern.
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