1. Ch. 4 Refraction (折射)

2. Incident
Ray
Refracted
Angle of
incidence
Angle of Refraction
air
glass
reflection
Reflected

3. Incident Rays (入射線) Refracted Rays (折射線) Normal (法線)
The light ray in air
Refracted Rays
(折射線)
The light ray in the glass block
Normal
(法線)
The line perpendicular to the glass block
Angle of incidence
(入射角)
The angle between the incident ray and the normal.
Angle of refraction
(折射角)
The angle between the refracted rays and the normal.

4. (r) is NOT equal to (i) (i = r = 0)
air
glass
i = 0
r = 0
air
glass
(r) is NOT equal to (i)
(i = r = 0)

5. i r
glass
air
Normal i r
air
glass
The light ray bent away from (偏離) the normal.
The light ray bent towards (偏向) the normal.

7. c

8. c 8

9. c 9

10. Experiment (實驗)
半圓膠塊 電源 光箱
量角器

11. Method
i / 30 45 60 75
r /

12. is a constant and is called refractive index (折射率) of glass.
sin i
0.500
0.707
0.866
0.966
sin r
is a constant and is called refractive
index (折射率) of glass.

13. Method
i / 30 45 60 75
r /

14. i / 30 45 60 75
r / 20 28 35 40
sin i
0.500
0.707
0.866
0.966
sin r
Correct to 3 significant figures. 14

15. refractive index (折射率) of glass.
sin i
0.500
0.707
0.866
0.966
sin r
is a constant (about 1.5) and is called
refractive index (折射率) of glass.

16. Laws of refraction (折射定律)
The ratio of the sine of the angle of incidence to
the sine of the angle of refraction is a constant.
= constant
The relation is called Snell’s law (斯湼耳定律).
The constant is called the refractive index (折射率)
of the material.

17. Refractive Index (折射率)
Material (物質)
Refractive Index (折射率)
vacuum (真空)
1.0000
air
1.0003
water
1.33
glass
1.5 to 1.7
diamond
2.42

18. 1. sin i is directly proportional (正比) to sin r.
Graphical Method to find Refractive Index
sin r
sin i
1. sin i is directly proportional (正比) to sin r.
2. The slope (斜率) of the graph is refractive index
of the material.

19. Class Exercise 6.1
i / 30 45 60 75
r /
sin i
0.500
0.707
0.866
0.966
sin r
Plot the graph of sin i against sin r in the graph paper.
(b) What is the relationship between sin i and sin r ?
(c) Hence, calculate the refractive index of the material.

20. i / 30 45 60 75
r /
sin i
0.500
0.707
0.866
0.966
sin r

21. (a)

22. (b) The graph is a straight line which passes through
Therefore, sin i is __________ to sin r.

23. (正比) to sin r. (b) The graph is a straight line which passes through
the origin (0,0)
Therefore, sin i is directly proportional
(正比) to sin r. 23

24. (c) slope = = =
The refractive index is 1.5