Calculate the angle of re'aclion when the angle of incidence at a glass surface is 55\" [refractive index of the glass = 1.48 ]. The absolute refractive index of 1[.vater is 1.3 and that of glass is 1.5. a) Calculate the relative refractive index. from glass to water. h) Explain what this implies regarding the refraction of light rays. c) Sketch a 1wavefront diagram to show how light travels through a plane interface from glass to water. Calculate the average critical angle for a material of average ahsolute refractive index 1.2. -1 At a distance of 15 In from the source, the intensity,r of a loud sound is Z x 10\" W In\". -1 a) Show that the intensity at 126 In from the source is approximately 3 x 105 W m\". h) Deduce how the amplitude of the wave changes. 16. The power radiated by the Sun is 3.9 x 1026 W. The distance between the Sun and the Earth is 1.5 x 1011 m. a) Calculate the intensity of the Sun's radiation at the upper atmosphere of the Earth. b) On a clear summer day 70% of this amount arrives at the surface of the Earth. Calculate how much energy is received by an area of 0.50 m in 1 hour