Refraction occurs when light travels from one medium to another of different densities, such as from air into water. When light travels into a denser medium, it bends toward the normal line, and when exiting a denser medium, it bends away from the normal line. This bending of light is called refraction. Refraction can cause mirages, where the refraction of light through layers of air of different temperatures causes images of the sky to appear as pools of water on hot days.

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.  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