To know how Refraction
light is refracted through
different medium.
What has happened in each example and why?
I think this is called...
It happens because...
The water is...
It happens when...
The air is...
The light usually travels...but
when it hits water...
To know how light is refracted through
different medium.
Success criteriaState why refraction happens.
Describe the direction light is refracted in
different situations.
Use the equation for refractive index.
To know how light is refracted through
different medium.
Observations• What do you notice about the angle of
refraction as the light ray enters the block
(from air into glass)?
• What do you notice about the angle of
refraction as the light exits the glass block
(from glass into air)?
Rectangular block air into block
angle of
incidence /
°
angle of
refraction /
°
deviation / °
Semi circle block (block into air)
angle of
incidence /
°
0
0
15
15
30
30
45
45
60
60
75
Observation
Rectangular block air into block
angle of
incidence /
°
0
angle of
refraction /
°
deviation / °
Face
1
1
45
60
75
deviation / °
Prism (block into air)
15
30
angle of
refraction /
°
Observation
angle of
incidence /
°
angle of
reflection / °
To know how light is refracted through
different medium.
How does Refraction work?
• As the light enters a glass block or water it is refracted
(bent) when it enters and leaves the lens.
Refraction of light at a plane surface
(a) Less to more optical dense transition (e.g. air to glass)
AIR
GLASS
normal
angle of
incidence
angle of
refraction
Light bends TOWARDS the normal.
The angle of refraction is LESS than the angle of incidence.
(b) More to less optical dense transition (e.g. water to air)
angle of
refraction
normal
angle of
incidence
WATER
AIR
Light bends AWAY FROM the normal.
The angle of refraction is GREATER than the angle of incidence.
2 different materials which have different
densities. The more dense a material the more
particles. Light can travel faster in air than it can
in a liquid or solid so it slows down when entering
them.
The Normal
line is always
90° to the
interface
When the incident ray enters
the glass block (doesn’t
matter about shape!) the ray
slows down and swings
TOWARD the Normal line.
The place where the 2
materials meet is
called the interface
When the
refracted ray or
Emergent ray
leave the glass
block it speeds
up again and
swings AWAY
FROM the
Normal.
To know how light is refracted through
different medium.
• www.upscale.utoronto.ca/PVB/Harrison/Flash
/Optics/Refraction/Refraction.html
To know how light is refracted through
different medium.
normals
observer
AIR
WATER
image
object at the
bottom of a pool
Why a pool appears shallow
To know how light is refracted through
different medium.
A
B
D
C
E
F
Complete the paths of the RED light rays:
To know how light is refracted through
different medium.
A
B
D
C
E
F
Complete the paths of the RED light rays:
To know how light is refracted through
different medium.
• Refractive index = sin i / sin r
• Using the table of values below, calculate the refractive
index of the medium. Suggest which material the medium
is made of.
Angle of
Incidence
24.0
24.0
24.0
63.0
47.0
Angle of
Refraction
15.7
9.76
18.2
36.4
29.2
Refractive
Index
Material
Material
Glass
Perspex
Diamond
Water
Refractive
Index
1.5
1.5
2.4
1.3
To know how light is refracted through
different medium.
Success criteriaState why refraction happens.
Describe the direction light is refracted in
different situations.
Use the equation for refractive index.
To know how light is refracted through
different medium.
1. Using the above equation calculate what the
angle of incidence must have been to give the
following angles of refraction in glass.
– 23°
– 33°
– 40°
2. A beam of light shines on a diamond block with
an angle of incidence of 15°. Calculate the angle of
refraction.
To know how light is refracted through
different medium.