1. Optical Phenomena

2. Angle of Refraction
All substances have a critical angle, an angle (not angel) at which light becomes trapped in a substance.
ni SinΘ = nr Sin θ
Nr is index of refraction of second medium
Ni is index of refraction of first medium
index of refraction are listed on page 490

3. Example 1:
Find the angle of refraction when light traveling through the air strikes the surface of crown glass at an angle of 30˚. Include a sketch of your results.

4. Based on the calculations you can determine a few things;
1….is light speeding up or slowing down as it enters the new medium
2…is light bent toward or away from the normal

5. Some phenomena…
Fiber Optics: thin flexible glass like strands that allow for internal reflection along the length but light exits easily at the end.
Mirages: light in the atmosphere encounters two air masses of different temperatures.

6. More…..
Rainbows: Light being refracted through water droplets. (Angle of inclination must be degrees)
Aberrations: “halo” effects around light sources. Can be caused by humidity in the air or lens curvature

8. Homework: Page 493 Practice A 1 and 2 (include diagram for #1)
Section Review 1-3 (include diagrams for #1 and 3)