Transcript REFRACTION AND REFLECTION POLARIZATION OF LIGHT

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Refraction is the change in direction of
a wave due to a change in its speed.
This is most commonly observed
when a wave passes from 1 medium
to another at an angle.
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Straight or bent? What happens when you
look at the pencil through the side of the
glass? Light play tricks on your eyes. The
pencil looks bent. This is because light
travels slower through water than through
air. As the light enters the glass of water it
slows down(changes direction) and as it
leaves the glass it speeds up again –
therefore making the pencil look as though it
is bent
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A lens is a piece of transparent
material. It is usually made of
glass and has at least one curved
surface.
The curved surface/surfaces of a
lens bends the light.
The angle of incidence is measured from the normal to
the incident ray.
The angle of refraction is measured from the normal to
the refracted ray.
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If light enters a more optically dense material,
the speed decreases and the light bends
towards the normal.
If light enters a less optically dense material,
the speed increases and the light bends away
from the normal.
Did you know....
A sunset is an optical illusion
Refraction allows you
to see the sun
even after it has set.
Reflection
Reflection
•Reflection- the return of light, heat, sound, etc.,
after striking a surface.
•bouncing of light off a mirror or mirror-like
surface.
Diffuse Reflection – reflection off an
irregular surface causing light to scatter
(no image)
Regular Reflection
reflection off a polished
surface (produces images)
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Polarized light vibrates on only 1 plane
Polarizing filters are used in photography
and some sunglasses
 Cornea:
transparent covering
of the front of the eye.
◦Allows for the passage of light
into the eye and functions as
a fixed lens.
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The iris regulates the size of
the pupil.
 Retina: lines the interior
surface of the eye
◦Contains photoreceptors.
Except where the optic
nerve attaches
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
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Mammals focus
light by changing
the shape of the
lens.
 The lens is flattened
for distant objects.
 The lens is rounded
for near objects.
 Photoreceptors
of the retina
◦rod cells - light sensitive but
do not distinguish colors.
◦cone cells - not as light
sensitive as rods but provide
color vision
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings