1. Learning Objectives
To observe and explain the phenomenon of refraction

2. How Does a Two-Way Mirror work?

3. Chapter 12 The Refraction of Light
12.1 What is Refraction?

4. Try This….
Light through water and glass
Penny in bowl with stir stick

5. Refraction
Refraction is the bending or change in direction of light when it travels from one medium to another.

6. Refraction: Why is the straw bent?
Khan Academy: Refraction

7. What Causes Refraction?
Analogy: A car rolling from pavement onto sand.

8. Refraction is caused by the wave front of light striking the surface of a new medium at an angle other than 90o.
This causes one part of the wave to change speed before the other part of the wave.

9. The Speed of Light In a vacuum: 3.00 x 108 m/s (300,000 km/s)
In water: x 108 m/s (226,000 km/s)
In acrylic: x 108 m/s (176,000 km/s)

10. The Rules of Refraction
Angle of Refraction: The angle between the refracted ray and the normal.
Light bends towards the normal when its speed decreases in a material.
Light bends away from the normal when the speed increases in a material.

12. Partial Reflection and Refraction
Refraction is often accompanied by reflection – called partial reflection and refraction.
Eg. Light striking water or a window
Few other materials have this dual property
Two-way mirrors and mirrored sunglasses reflect much of the incident light.

14. ROY G BIV says: p. 519 # 1-5 Read p. 515 – 519
Lab Activity: Path of Light from Air to Acrylic
You need a calculator for the rest of this unit!

15. How Does a Two-Way Mirror work?