c explain the concept of the fresnel zones derive an expression for the area of the first fresnel zone and calculate the area for a 600 nm at a distance b lmm from the centre of the wavefron 69479

(c) Explain the concept of the Fresnel zones: Derive an expression for the area of the first Fresnel zone and calculate the area for A = 600 nm at a distance b = lmm from the centre of the wavefront: (d) Figure 3 shows the setup to obtain Fresnel diffraction from a straight edge. Figure 3: Source (S) Obstacle Screen Sketch the diffraction pattern expected at the screen. Mark on your diagram the approximate positions corresponding to PO, P1 and P2. ii. Provide a sketch of the Cornu spiral for the above situation and draw a line on the sketch corresponding to the maximal amplitude. Explain how the intensity at this point relates to the length of the line on your drawing:

In the single-slit diffraction experiment of Fig. $36-4,$ let the wave-length of the light be 500 $\mathrm{nm}$ , the slit width be $6.00 \mu \mathrm{m},$ and the viewing screen be at distance $D=3.00 \mathrm{m}$ . Let a $y$ axis extend upward along the viewing screen, with its origin at the center of the diffraction pattern. Also let $I_{P}$ represent the intensity of the diffracted light at point $P$ at $y=15.0 \mathrm{cm} .\left($ a) What is the ratio of $I_{P}$ to the intensity $I_{m \text { at }}\right.$ the center of the pattern? (b) Determine where point $P$ is in the diffraction pattern by giving the maximum and minimum between which it lies, or the two minima between which it lies.

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