1. Refraction

2. Learning goals We are learning why light bends.
We are learning to calculate the index of refraction.

3. refraction when light enters a new medium it changes speed
the speed of light is dependent on the substance (medium) it is travelling in

4. Refraction
the bending of light as it moves from one medium to another.
Medium examples – air, water, oil, glass, etc.

5. refraction

6. Cause of refraction
light will bend towards the normal when its speed decreases
light will bend away from the normal when its speed increases

7. Apparent depth
the depth an object appears to be at due to refraction of light in a transparent medium

8. every medium has an index of refraction (n), the ratio of the speed of light in a vacuum to the speed of light in the medium
Index of refraction

9. Snell’s Law used to calculate the refractive index (n): Where:
c = 3.0 x 108 m/s
v = speed of light in medium
n = refractive index

10. What is the refractive index of material in which light travels at 2
What is the refractive index of material in which light travels at 2.5 x 108 m/s?
Example #1

11. How quickly would light travel in a material with a refractive index of 1.75?
Example #2

12. Learning goals We are learning why light bends.
We are learning to calculate the index of refraction.

13. P519 #2-4
P525 #2,3,6-8
Homework