refraction and reflction
DESCRIPTION
TRANSCRIPT
ReflectionReview
NORMAL LINE
PERPENDICULAR
INCIDENCE
INCIDENT
40 ͦ� ͦ ͦ ͦ ͦ ͦ ͦ ͦ ͦ
REFLECTION
REFLECTED
Slide ͦ4 ͦ
Law of Reflection
qi = qr
Refraction
The change in direction of a wave as it crosses the boundary between two media in which the wave travels at different speeds.
Index of Refraction
materialinlightofspeed
vacuuminlightofspeedn
Index of RefractionMaterial Index of RefractionVacuum 1.0000
Air 1.0003Ice 1.3100
Water 1.3330Ethyl Alcohol 1.3600
Plexiglas 1.5100Crown Glass 1.5200
Light Flint Glass 1.5800Dense Flint Glass 1.6600
Zircon 1.9230Diamond 2.4170
Rutile 2.9070Gallium phosphide 3.5000
Index of refraction of air
Speed of light In vacuum 299, 792 km/sIn air 299,705 km/s
n= 299, 792 km/s / 299, 705 =1.0003
Index of refraction of waterSpeed of light
In vacuum 299, 792 km/sIn water 224, 900 km/s
n= 299, 792 km/s / 224, 900 =1.3330
Snell’s Law
2211 sinsin nn
ExampleLight travels from air into an optical fiber with an
index of refraction of 1.44. (a) If the angle of incidence on the end of the fiber is 22o, what is the angle of refraction inside the fiber?
n1 = 1.00
n2 = 1.44
θ1 = 22o
(1.00) sin 22o = 1.44 sin θ2.
(1.00/1.44) sin 22o = sin θ2
0.260 = sin θ2
sin-1 (0.260) = θ2
15o= θ2
2211 sinsin nn
Worksheet
Label the following diagramAngle of Incidence
Incident Ray
Normal Line
Refracted Ray
Angle of Refraction
n= 299, 792 km/s / 169, 500 km/s =1.76
Substance Speed of Light in
Substance
Refractive Index
Sapphire 169,500 km/s 1.76
1.36 sin45 o = 2.42 sin θ2. (1.36/2.42) sin 45o = sin θ2
0.40 = sin θ2
sin-1 (0.40) = θ2 23.58o= θ2
45 ͦ�
24 ͦ�
Water:1.00 sin40 o = 1.33 sin θ2. (1.00/1.33) sin 40o = sin θ2
0.40 = sin θ2
sin-1 (0.40) = θ2 28.90o= θ2
Perspex:1.00 sin40 o = 1.5 sin θ2. (1.00/1.5) sin 40o = sin θ2
0.40 = sin θ2
sin-1 (0.40) = θ2 25.37o= θ2
Angle of Incidence (in air)
Angle of refraction in water (nwater = 1.33)
Angle of refraction in perspex (nperspex = 1.5)
40 � 28.90 25.37
Which arrow point the real position of the fish and which arrow point the position of the fish’ image (from the man’s position?)