2. What do you mean by harmonic motion? Give a graphical comparison among the following four types of harmonic motion: i) simple harmonic motion, ii) underdamped harmonic motion, iii) overdamped harmonic motion and iv) critically damped harmonic motion. 3. a) Deduce Brewster's law. b) Find the Brewster's angle of a glass slab of refractive angle 1.5. If the slab is immersed in water of refractive index 4/3, find the angle of polarization. 4. What do you mean by irrotational vector? Show that (611+); + (3)j + (3122) is irrotational. 5. Write down the expression for the intensity of light due to Fraunhofer diffraction in a single slit and hence find the conditions for maxima and minima in the diffraction pattem.