OBJECTIVES: Explore the refraction property
of light. Determine what causes
bending of light. Relate refraction of light to real
life experiences.
REFRACTIONIs the BENDING of light as it passes OBLIQUELY from one medium to another of different optical density.
Examples:Air to waterWater to airWater to glass
Why does LIGHT bend?
Light bends because….1. Of the change in
MEDIUM.Light bends as it moves from one medium to another like from air to water.
Light bends because….1. It changes
speed as it encounters a different medium.
Light does not bend when it enters the medium perpendicularly, however it slows down.
glassairIncident
ray
Refracted ray
Normal line
1
2
Angle of incidence
Angle of refraction
What determines the bending of light?
When light enters a medium of greater optical density, it bends towards the normal.
less dense
denser medium
i
r
i = angle of incidence
r = angle of refraction
i > r
Normal lineincident ray
refraction ray
less dense
denser medium
i
r
i = angle of incidence
r = angle of refraction
Normal lineincident ray
refraction ray
Light rays bend towards the normal when the rays travel from a less dense medium to a denser mediumLight rays travel much slower in a denser medium
air
glass
air
water
When light enters a medium of lesser optical density, it bends away from the normal.
denser medium
less dense
i
r
i = angle of incidence
r = angle of refraction
i < r
Normal lineincident ray
refraction ray
Light rays bend away from the normal as it travels from a denser medium to a less dense medium.Light rays travel much faster in a less dense medium
denser medium
less dense
i
r
i = angle of incidence
r = angle of refraction
incident ray
refraction ray
air
glass
air
water
LIGHT ENTERING WATER FROM AIR
INDEX OF REFRACTION (n).The ratio of the speed of light in vacuum to the speed of light in the material.
Speed of light in vacuumSpeed of light in material
= =n Cv