1. Refraction

2. Refraction
Light can bend not only when it reaches a reflective surface but also when it goes from one medium to another
Medium (pl. media)
The substance or material that light is traveling through

3. Identify the media through which light is traveling in this example.
Describe what happens to the wave of light.

6. Can you think of other examples of refraction between air and water?
Identify the media through which light is traveling in this example. (What is the fisherman’s problem?)
“Come here, fishy fishy…”
Can you think of other examples of refraction between air and water?

8. Refraction
The change in the direction of light when it crosses a boundary between two media.
The effect is only noticeable when the media have different densities.

9. Densities
Order the list of materials from least to most dense: water, glass, air
Air
Water
Glass
When light travels between these media it will change direction
It will slow down as it goes from less dense to more dense
or speed up as it goes from more dense to less dense

10. What causes refraction?
normal
incident ray
Because water is more dense than air the refracted ray slows down which bends the angle towards the normal i
air
water
refracted ray R
angle of refraction (R)

11. Water reflects and refracts light
At large angles of incidence most of the light reflects and less refracts

12. Water reflects and refracts light
At small angles of incidence most of the light enters the water and refracts
This explains why you only see a small area underwater directly under where light penetrates the water.

13. Predict what will happen to the refracted ray in each case:
normal
air
Incident ray i
glass
Will the refracted ray bend towards or away from the normal?

14. Predict what will happen to the refracted ray in each case:
normal
air
Incident ray i
glass R
The angle of refraction is smaller (glass is more dense so light slows down) and the refracted ray will be bent towards the normal.

15. Predict what will happen to the refracted ray in each case:
normal
water
Incident ray i
air
Will the refracted ray bend towards or away from the normal?

16. Predict what will happen to the refracted ray in each case:
normal
water
Incident ray i
air R
Refracted ray
The angle of refraction is greater (air is less dense so light speeds up) and the refracted ray will be bent away from the normal.