Warm up Go to the online textbook and open chapter 14 Complete problems 15-19 on p. 386
Behaviors of Waves Interference – two waves occupy the same space at the same time Constructive – combine to produce a larger wave Destructive – waves subtract from each other or cancel each other out completely
Reflection – a wave strikes an object and bounces off
Total Internal Reflection The critical angle of incidence has been exceeded; a wave (light) strikes an object and is continually reflected throughout a material. Ex.: Fiber optic cable
Critical Angle Θ c = n 2 /n 1 For air, sinθ c = 1/n 1
Example 1 The index of refraction for water is 1.33. Above the water is air. What is the critical angle of incidence for light starting inside the water and passing into the air above it?
Example 2 A diamond with an index of refraction of 2.42 is surrounded by air. If a ray of light originating inside the diamond strikes the surface of a facet at an angle of 27 degrees from the normal, will the ray be refracted or will it experience total internal reflection?
Diffraction Diffraction – a wave passes through an opening and bends and changes direction
Refraction - waves bend and change directions and speed when they travel from one medium into another
Law of Refraction (Snell’s Law) n 1 sinθ 1 = n 2 sinθ 2 n=index of refraction (different for every medium) n(air) = 1.00
Example 1 A ray of light passes through air and strikes a piece of glass at an angle of 45 degrees from the normal. If the index of refraction of glass is 1.60, what will be the angle of refraction?
Example 2 Light passes through air and strikes the surface of a piece of glass at an angle of 58 degrees from the normal. The angle of refraction is 33 degrees measured from the normal. Calculate the index of refraction for the glass.
Polarization of Light When light passes through two polarized filters perpendicular to each other, light is completely blocked.
Doppler Effect Change in frequency perceived by an observer moving relative to a wave source.