January 2023

DAY 19 – DAW January

Production and detection of linearly and circularly polarized light; Double refraction, quarter wave plate; Optical activity; Principles of fibre optics, attenuation; Pulse dispersion in step index and parabolic index fibres; Material dispersion, single mode fibres; Questions: Q 1. For a multimode step-index optical fibre, the core refractive index is 1.5 and the fractional index difference

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DAY 17 – DAW January

Fraunhofer diffraction-single slit, double slit, diffraction grating, resolving power; Diffraction by a circular aperture and the Airy pattern; Questions: Q 1. Can D1 and D2 lines of sodium light be resolved in second-order spectrum if the number of lines in the given grating is 450? Explain.   λD1=5890A0\lambda_{D1}=5890 A^0λD1​=5890A0 and  λD1=5890A0\lambda_{D1}=5890 A^0λD1​=5890A0. [10 marks] Q

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DAY 15 – DAW January

Interference of light-Young’s experiment, Newton’s rings, interference by thin films, Questions: Q 1. What are Newton’s rings? How are they formed by two curved surfaces ? [10 marks] Q 2. A soap-film of refractive index 1.33 is illuminated with light of different wavelengths at an angle of 45°45\degree45°. There is complete destructive interference for λ\lambdaλ

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DAY 13 – DAW January

Laws of reflection and refraction from Fermat’s principle; Matrix method in paraxial optics-thin lens formula, Questions: Q 1. State and explain the Fermat’s principle of extremum path. Discuss the cases of rectilinear propagation of light and reversibility of light rays in the context of Fermat’s principle. Using Fermat’s principle, deduce thin lens formula. [15 marks]

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