intensity of a monochromatic light equation

However, when rays travel at an angle θ θ relative to the original direction of the beam, each ray travels a different distance to a common location, and they can arrive in or out of phase. When they travel straight ahead, as in part (a) of the figure, they remain in phase, and we observe a central maximum. (Each ray is perpendicular to the wave front 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 wave front in the slit emits wavelets, as we discussed in The Nature of Light. We then consider light propagating onwards from different parts of the same slit. Here, the light arrives at the slit, illuminating it uniformly and is in phase across its width. The analysis of single-slit diffraction is illustrated in Figure 4.4. (b) The diagram shows the bright central maximum, and the dimmer and thinner maxima on either side. The central maximum is six times higher than shown.

(a) 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 ( Diffraction Gratings) produces evenly spaced lines that dim slowly on either side of the center.įigure 4.3 Single-slit diffraction pattern. Note that the central maximum is larger than maxima on either side and that the intensity decreases rapidly on either side. Figure 4.3 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, which we discussed in the chapter on interference.

For example, if you place your middle and index fingers close together and look through the opening at a light bulb, you can see a rather clear diffraction pattern, consisting of light and dark lines running parallel to your fingers. However, situations do occur in which apertures are small enough that the diffraction of light is observable. Since the wavelengths of visible light range from approximately 390 to 770 nm, most objects do not diffract light significantly. The diffraction of sound waves is apparent to us because wavelengths in the audible region are approximately the same size as the objects they encounter, a condition that must be satisfied if diffraction effects are to be observed easily. (credit: modification of map data from Google Earth) It implies that there is a path difference in the Young double-slit experiment between the two slits S 1 and S 2.Figure 4.2 Because of the diffraction of waves, ocean waves entering through an opening in a breakwater can spread throughout the bay. When the slit separation ‘d ‘and the screen distance D are kept unchanged, to reach point P the light waves from slits S 1 and S 2 must travel at different distances. Thus, an interference pattern takes place when both the slits S 1 and S 2 are open.The S 1 is opened, S 2 is closed and the screen opposite to the S 1 is closed, but the screen opposite to S 2 is illuminating. It is considered that d is the separation between both the slits. The light passes through these slits and falls on the screen that is kept at the distance D from both the slits S 1 and S 2.SO, we can assume that S 1 and S 2 are two coherent sources derived from S. Consider a monochromatic light source ‘S’ kept at a relevant distance from two slits namely S 1 and S 2. Considering two waves interfering at point P, having different distances.

Intensity of a monochromatic light equation