Topic
Displacement
Vectors
2
3 Kinematics
4 Graphs
5 Energy
6 Power
7 Springs
8 Shadows
9 Field of Vision
10 Colors
11 Concave mirrors
12 Convex mirrors
13 Refraction
14 Lenses
15 Optical Power
1
Slides Minutes
9
27
13
39
13
39
10
30
10
30
5
15
4
12
3
9
7
21
3
9
7
21
4
12
5
15
10
30
6
18
Refraction is the bending of light rays as they pass from one
medium into another medium of different optical density.
The index of refraction of a transparent medium is a ratio of the
speed of light in a vacuum to the speed of light in the medium:
n = c/v
where
n = is the index of refraction (no units)
c = 3 x 108 m/s
v = speed of light in the medium (in m/s)
Note : The greater the index of refraction of a medium,
the slower light travels in that medium.
The index of refraction for a vacuum is 1, for water it is 1.33,
for diamond it is 2.42, etc.
The highest of any natural material
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When refraction occurs, light bends away from the normal when the
optical density (index of refraction) is less dense (and vice versa).
The following illustration demonstrates this fact:
n1 = 1
Normal
n2 = 1.5
n1 < n2
n1 = 1.5
Normal
n2 = 1
n1 > n2
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Refraction Slide: 13. 1
A light ray passes from air into a liquid as illustrated below.
Determine the index of refraction for this liquid.
Step-1: Determine the angle of incidence
and the angle of refraction.
i
r
Step-2: Calculate the index of refraction
using Snell’s Law.
A) 1.5
B) 1.4
C) 0.72
D) 0.65
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Refraction Slide: 13. 2
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Refraction Slide:
13. 3
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Refraction Slide: 13. 4
Away from
normal
Away from
normal
Towards
normal
Away from
normal
Because n 1is greater than n2 , the refracted ray
bends AWAY from the normal.
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Refraction Slide: 13. 5
REMEMBER
Critical angle means the angle of refraction is 90o.
Click
… and good luck!