1. Refraction

2. What is Refraction?
The bending of light as it travels from one medium to another.

3. Examples of Refraction
A spoon appears bent as it enters water.
Attempting to
touch an object
under water and
missing it.

5. Examples of Refraction
Seeing an object just under the surface of water in a dish, when you could not see it without the water (Bill Nye!)

6. What Causes Refraction?
The speed of light is different in different mediums.
You see things because of the light rays reflecting from them
As rays pass through a boundary, the light rays speed up or slow down causing them to bend

7. Analogy…..
Wagons travelling from a paved road to sand.

8. Explanation…..
As the right front wheel hits the sand, the wagon changes direction because the wheel in the sand turns slower.

9. Refraction
Fast Medium
Slow Medium

11. Relative Speeds of Light
Faster
Slower
Vacuum
Air
Water
Acrylic (clear plastic)

12. The thicker the medium, the slower the light goes
Thickness is known as optical density (reflected in the index of refraction value)

13. Refraction Light Rays incident ray refracted ray angle of refraction
angle of incidence
angle of refraction

14. Rules for Refraction
The incident ray and the refracted ray are on opposite sides of the line that separates the two media.

15. Rules for Refraction
Light bends towards or away from the normal depending on the speed of light in the second medium.

16. Rules for Refraction
Light bends toward the normal if it travels more slowly in the second medium than in the first.

17. Faster to slower medium Slower to faster medium
Bends towards the normal
Slower to faster medium
Bends away from the normal

18. Rules for Refraction
Light bends away from the normal if it travels faster in the second medium than in the first.

19. Partial Reflection Reflection and refraction often happen together.
Light hitting the water reflects off the water, but also refracts as it enters the water illuminating objects below the water.

20. Reflection AND Refraction

21. Examples of Partial Reflection
Glass may have special film to allow light in, but reflect incident light as well.(mirrored buildings)
Mirrored surfaces you can see through, but
others cannot!
(sunglasses)

22. Refraction Angle of Refraction
Vocabulary!
Refraction Angle of Refraction

23. Homework!
Pg. 519 #2 – 5