Chapter 17 Reflection and Refraction

Ch 17.1 How light behaves at a boundary

I How light behaves at a boundary A. The law of reflection B. The refraction of light C. Snell’s law D. Index of refraction and the Speed of light

A. Law of Reflection Regular reflection Diffuse reflection

B. Refraction of Light Bending of light at a boundary Angle of refraction Optical density

C. Snell’s law The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant. Index of refraction n = sin θ i /sin θ r Snell’s law n i sin θ i = n r sin θ r

PSS Drawing ray diagrams 1. Draw a diagram showing the two media. 2. Label the media and indicate the two indices of refraction 3. Draw the incident ray to the point where it hits the surface, then draw a normal to the surface at that point. 4. Use a protractor to measure the angle of incidence.

5. Use Snell’s law to calculate the angle of refraction 6. Use a protractor to draw the refracted ray leaving the surface at the point where the incident ray entered. 7. Evaluate your work.

Index of Refraction and the Speed of light Recall that when a wave moves from one medium to another where the wave speed is different, the frequency does not change. v = f v = f material = v material /f Index of refraction n substance = c/v substance

Homework: –Chapter 17 review problems