1. Reflection and Refraction

2. Law of Reflection • Angle of reflection = Angle of incidence

3. Specular vs. Diffuse Reflection Think about bouncing a basketball on smooth surface vs. gravel road!

5. Refraction http://www.upscale.utoronto.ca/PVB/Harrison/Flash/Optics/Refraction/Refraction.html Mirage – occurs when there is a rapid shift in air density, air is hotter at surface!

6. Penny and Cup Activity

7. Index of Refraction • Ratio of the speed of light in a vacuum to the speed of light in a particular substance • Constant that is characteristic of a substance There are no units!

8. Snell’s Law • A ray bends in such a way that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant. n1sinθ1 = n2sinθ2 incident angle refracted angle Index of incident medium Index of refracted medium

10. Snell’s law examples • 15A Q1 • 15A Question 4 • 15 131 Q1

11. Total Internal Reflection • Occurs when light moves from high optically dense medium to a low optically dense medium at an angle so great there is no refracted ray http://www.rebeccapaton.net/rainbows/tir.htm#Total%20Internal

12. Criteria for TIR • High to low optically dense medium • Angle of incidence must be greater than critical angle Critical angle - sin θc = nr ni -Minimum angle of incidence for which TIR occurs -At an instance a refracted ray moves parallel to the boundary, making θr equal to 90°