1. Chapter 15.1

2.   Reflection is the turning back of light.  All objects reflect some or all of its light.  Refraction is the bending of light.  Transparent objects bend light when passing through them (refraction). Reflection vs. Refraction

3.   Refraction – The bending of wave disturbance as it passes at an angle from one medium into another.  Ex:  Light passing from air to water bends as it goes from one medium to another. Refraction

4.   Imagine two wheels on an axel rolling across two different surfaces. Refraction Example Blacktop Grass Blacktop 1 2 3

5.  1.Left Wheel hits the grass first and slows down as the right wheel continues at its original speed. This causes the wheels and axel to change from its original direction. 2.Once both wheels are in the grass, they both travel at the same speed (No Bending). 3.Left wheel leaves the grass first making it speed up again as the right wheel is still slowed by the grass causing the wheels and axel to turn again. Back to its original direction, just shifted. Explanation

6.   The same thing happens to light when it passes from one medium to another just as the wheels traveled from one surface to another.  Ex:  Air to Glass  Air to Water  Water to Air  Etc… Refraction Explanation

7.  The Law of Refraction

8.   There is no bending of light when the index of refraction is equal to one (n = 1).  Index of refraction is unitless.  For all index of refraction values greater then one (n > 1), light bends from it’s original path.  As the value of “n” increases the bending of light increases.  Ex:  Diamond: n = 2.419  Water: n = 1.333  Air: n = 1.000293 Index of Refraction

9.   The wavelength of light also effect the index of refraction.  Ex:  White light passing through a raindrop let (water) and creating a rainbow.  ROYGBIV  Red – Low Bend  Violet – High Bend Wavelength and Refraction

10.  Snell’s Law

11.  Snell’s Law Diagram Normal Line AIR Water

12.   A light ray traveling through air strikes a smooth, flay slab of crown glass at an angle of 30 degrees to the normal. Find the angle of Refraction. Snell’s Law Example

13.  Example Answer