1. Light of wavelength 686 nm in air enters water, making an angle of 40.4 with the normal. Determine a) the angle of refraction and b) the wavelength of light in water. Explain your working. (The refractive index of water is 1.33) 2. The power radiated by the Sun is 3.9 1026 W. The distance between the Sun and the Earth is 1.5 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. 3. A stone dropped in still water creates circular ripples that move away from the point of impact, Z. The height of the ripple at point P is 2.8 cm and at point Q it is 1.5 cm. Calculate the ratio of the energy carried by the wave at P to that at Q. 4. Red light of wavelength 6.8 10-7 m in air enters glass with a refractive index of 1.583, with an angle of incidence of 38 degrees. Calculate the following given the information: a) the angle of refraction b) the speed of light in the glass c) the wavelength of light in the glass. 5. Light of frequency 6.0 1014 Hz is emitted from point A and is directed toward point B a distance of 3.0 m away. a) Determine how long will it take light to get to point B. b) Calculate how many waves fit in the space between point A and point B. displacement/cm 6. Calculate the phase difference between the two displacement-time graphs show in below. Give your answers in a) seconds; b) radians; c) degrees. displacement/cm 2.5 2.0+ 1.5 1.0- 0.0 1.0 2.0 time/s 0.5- 0.0 -0.5- -1.0+ -1.5 -2.0- -2.5 3.0 4.0 5.0 2.5 2.0- 1.5 1.0- 0.5- AA 0.0 -0.5 -1.0- -1.5- -2.0- -2.5 0.0 1.0 2.0 3.0 4.0 5.0 time/s 7. At a distance of 15 m from the source, the intensity of a loud sound is 2.0 10-4 W m- a) Show that the intensity at 120 m from the source is approximately 3 x 10-6 W m-. b) Deduce how the amplitude of the wave changes. 8. Calculate the angle of refraction when the angle of incidence at a glass surface is 55 degrees (refractive index of the glass =1.48) 9. The (absolute) refractive index of water is 1.3 and that of glass is 1.5. a) Calculate the relative refractive index from glass to water. b) Explain what this implies regarding the refraction of light rays. c) Draw a wavefront diagram to show how light travels through a plane interface from glass to water. 10. Calculate the (average) critical angle for a material of (average) absolute refractive index 1.2.