Refraction occurs at a boundary The speed of light must change at the boundary The angle of the light ray is measured from the normal as was the case with reflection If the speed slows across the boundary the refracted angle will be smaller the light ray will bend toward the normal ID: 491068
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Slide1Slide2
Refraction is bending of light rays
Refraction occurs at a boundary
The speed of light must change at the boundary
The angle of the light ray is measured from the normal, as was the case with reflectionSlide3
If the speed slows across the boundary, the refracted angle will be smaller – the light ray will bend toward the normal.
If the speed increases across the boundary, the light ray will bend away from the normalSlide4
Refraction
Refraction is the bending of light when it enters from one transparent medium into another.
It is caused by the different speeds of light in different media.
The greater the optical density of the medium, the slower the speed of light.Slide5Slide6
Incident ray
Refracted ray
Emergent ray
Angle of incidence
Angle of refraction
normal
Angle of emergenceSlide7
Laws of Refraction
The incident ray, the refracted ray and the normal all lie in the same plane.
For two particular media, the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant.
(Snell’s Law
)Slide8
Refractive Index
When light passes from vacuum (or air) into a given medium (eg. water), the constant ratio is known as the refractive index,
n
, for that medium.
Angle of incidence
Angle of refractionSlide9
Index of Refraction
Medium
Index of refraction = n
Vacuum
1
Water
1.33
Lucite
1.5
diamond
2.4
Slide10
From less dense to more dense
From more dense to less denseSlide11
Daily Phenomena of Refraction
Swimming pool and ponds appear shallower than it really is.
Object is at a deeper depth than where it appears to be.
Bent objects in liquidsSlide12
I See You – You See Me
Notice that the fish appears
more shallow to the person.Slide13
On a hot summer day, as you drive down a road, you see what appears to be the reflection of an oncoming car in a pool of water.
The pool, however, disappears as you approach it.
Mirage
s
Refraction of LightSlide14
Mirages
The mirage is the result of the Sun heating the road.
The hot road heats the air above it and produces a thermal layering of air that causes light traveling toward the road to gradually bend upward.
This makes the light appear to be coming from a reflection in a pool.