15. In a single-slit diffraction experiment, the slit is exposed to white light. What colour is the fringe surrounding the central fringe? (10.2) ku (a) red (b) yellow (c) violet (d) green 16. A ray of light strikes a glass plate at an angle of incidence of 60". The reflected and refracted rays are perpendicular to each other. What is the index of refraction of the glass? (10.5) kru (a) V5 (b) V3 (c) V2 (d) 3 17. Which of the following statements is correct? (10.5) Ku (a) Brewster's angle is independent of the wavelength of light. (b) Brewster's angle is independent of the nature of the reflecting surface. (c) Brewster's angle is different for different wavelengths. (d) Brewster's angle depends on the wavelength but not on the nature of the reflecting surface. 18. When unpolarized light of intensity I is incident on a polarizing sheet, the intensity of the light that does not get transmitted is (a) (b) C (d) I (10.5) KU