1. (a)Distinguish between Fraunhofer and Fresnel diffractions. (5 marks) (b) Parallel rays of light with wavelength λ = 500 nm are incident on a slit of width a = 0.2 mm. A diffraction pattern is formed on a screen at a distance D=2.5 m from the slit. Find the position of the first minimum and the width of the central bright fringe. 2. (a) Describe Brewster's angle for a diamond submerged in water. (2.5 marks) (c) White light containing wavelengths from 400 nm to 750 nm strikes a grating containing 4000 slitsem¹. Determine that the blue light, λ = 450 nm of the third-order spectrum overlaps the red light, λ = 700 nm of the second order. (3 marks) (2.5 marks) (b) Explain the advantage of polarized sunglasses over plain tinted sunglasess. (2.5 marks)
(c) A series of polarizers are each rotated 10° from the previous polarizer. Unpolarized light is incident on this series of polarizers. Calculate the total polarizers that light have to go through before achieving 1/5 of its original intensity. (3 marks) (d) Unpolarized light of Io passes through six successive polaroid sheets each of whose axis makes a 35° angle with previous one. Find the intensity of the transmitted beam. (2.5 marks)
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