2. bending of a ray of light
when passing from one medium to another (at an angle) because the wave changes speed
Remember, the medium determines the speed of light.

3. When light travels from a less dense to
more dense medium (light slows down),
the ray is refracted toward the normal.
Example: light slows down when it passes from air into water n i
air i
> r
water r

4. i r i < r n Example: light speeds up when passing from
When light travels from a more dense
medium to a less dense medium (light speeds up),
the ray is refracted away from the normal.
Example: light speeds up when passing from
glass into air
air i n r
glass i
< r

5. Concept Check
Click for Answer

6. Multiple medium refraction
More Refraction
Multiple medium refraction

7. Refraction is responsible
for the separation of light into
colors, because shorter wavelengths refract more than longer wavelengths.
Violet refracts more than longer red

8. Concept Check
Click for Answer

9. The properties of light responsible rainbows are reflection and refraction.

10. Mirages
When air near ground gets very hot and causes light to refract (bend) upwards

11. speed of light in a vacuum (c) speed of light in that substance (v)
index of refraction (n)
speed of light in a vacuum (c)
divided by
speed of light in that substance (v)
n = c / v

12. The larger the index of refraction, the slower light travels through the substance.

13. Total Internal Reflection
When the incident angle becomes very large, no light can be refracted.
All light is reflected back to the original medium. The light appears to be trapped.
Fiber optics transmit information through total internal reflection.

14. Lens Math
Just like mirrors
and

15. Lens Math Signs f = focal length (+) converging lens
(-) diverging lens
do = object distance
(+) in front of lens
(-) in back of lens
di = image distance
(+): In back of lens
(-): In front of lens

16. Microscopes and Telescopes
Compound Microscope
Refracting Telescope

17. Eyeglasses A Healthy 20/20 eye
Hyperopia – corrected with a converging lens
Myopia – corrected with a diverging lens

18. Concept Check
Click for Answer

19. Practice Problem
A real image is produced by a converging lens with a focal length of 15 cm. If the object is 10 cm tall and 21 cm in front of the lens:
Where is the image located?
How tall is the image?
Is the image magnified or reduced?

20. Soap Bubbles (and other thin films)
The properties of light
responsible for the separation of light into
colors by a soap bubble (or other thin films)
are reflection, refraction, and interference.
Interference is defined as the result of the
superposition of two or more waves.