1. Aim: What happens to the speed of light in different mediums? Do Now: What is the wavelength of yellow light? v = f λ c = f λ 3 x 10 8 m/s = (5.20 x 10 14 Hz) λ λ = 5.8 x 10 -7 m

2. Index of Refraction (n) Equal to ratio of speed of light (c) in vacuum to speed of light in material Equal to ratio of speed of light (c) in vacuum to speed of light in material Indicator of optical density Indicator of optical density

3. These are the indices of refraction (n)

4. A ray of monochromatic light passes through a flint glass prism. What is the speed of the light ray in flint glass? n = c/v 1.66 = 3.00 x 10 8 m/s v v = 3.00 x 10 8 m/s 1.66 1.66 v = 1.81 x 10 8 m/s

5. In a certain material, a beam of monochromatic light (f=5.09 x 10 14 Hz) has a speed of 2.25 x 10 8 m/s. What is the material? n = c/v n = 3.00 x 10 8 m/s 2.25 x 10 8 m/s 2.25 x 10 8 m/s n = 1.33 WATER

6. Speed of light is constant… Large n  small v Large n  small v Small n  large v Small n  large v

7. Optical Density Velocity of the wave in the new medium depends on optical density. Velocity of the wave in the new medium depends on optical density. The more dense, the slower the velocity The more dense, the slower the velocity Determines the direction and degree to which the ray will bend upon entering the new medium. Determines the direction and degree to which the ray will bend upon entering the new medium.

8. A beam of monochromatic light travels through flint glass, crown glass, lucite, and water. The speed of the light is slowest in (1) Flint glass (2) Crown glass (3) Lucite (4) Water

9. Relationship between n, v, and λ We know: We know: and and So we can say: