1. Refraction
Topic #3

2. Refraction
You know that reflection occurs when light rays bounce off objects and we can now predict the manner in which they bounce off
But what happens when light travels from one medium to another e.g. from air into water???

3. If you’ve ever stood on the edge of a pool and tried to dive for an object,
you might have found that
the object was not where
you thought it was
Refraction is the bending
of light when it travels from
one medium to another

5. When light travels from one medium into a denser one (air into water), the light will bend towards the normal
When light exits a denser medium, its direction of travel bends away from the normal
The new direction of light is called the angle of refraction, R

7. Refraction can occur when light travels through air at different temperatures (warm air is less dense than cold air)
The refraction of light through air of different temperatures can cause a mirage.

8. Mirages
Example: driving down the highway on a hot day and it looks like there are pools of water lying ahead
The air close to the ground is hotter and less dense than the air higher up
Light from the sky directed at the ground is bent upwards as it enters the less dense air
The “pools of water” are actually images of the sky refracted by warm air near the ground

10. What happens to the light?
The table below describes what happens to light when it strikes different surfaces
Sometimes all 3 light behaviors happens at once
Type of behavior
What happens to the light?
Nature of the surface
What else happens?
Absorption
Changes into some other form of energy
Rough, dark, opaque surfaces
Some light is reflected off the surface
Reflection
Bounces off and travels in a new direction
Smooth shiny surface
Some light is usually absorbed
Refraction
Travels through the surface in a new direction
Light strikes a different, transparent material
Some light is usually reflected off the surface