Transcript Light - Warren Consolidated Schools

Light
Benchmarks
Describe ways in which light interacts
with matter.
Explain how light is required to see
objects.
Misconceptions
There are an incredible amount of
misconceptions associated with light.
30 are listed here…
Even more misconceptions are
associated with color and vision.
Another 20 are listed here…
Light is energy that travels in waves.
When this energy hits an object it may…
– Transmitted – passes through
– Absorbed – does not pass through
– Reflected – bounces off
Transmission of Light
If light is being transmitted through something it
is somehow passing through it.
– It may produce a clear image by having the light pass
directly through something that is transparent.
– It may produce an unclear image by having the light
pass part of the way through something that is
translucent.
– Or it may produce a broken or bent image by having
the light bend or be refracted due to it moving from
one media or state of matter to another.
Absorption of Light
Different materials
Color
Video (02:15)
Reflection of Light
Reflection occurs when a light wave strikes
an object and bounces off.
– Regular reflection- Smooth surfaces reflect light
in one direction. (mirror)
– Diffuse reflection- Rough surfaces scatter light in
many directions. (paper)
– See
http://www.lewport.wnyric.org/mgagnon/light.html
Angle of Reflection = Angle of
Incidence
Image
http://laser.physics.sunysb.edu/~amy/wise2000/websites/Mi
rror348.jpg
Mirror348.jpg
Animation
http://www.glenbrook.k12.il.us/gbssci/phys/mmedia/optics/lr
.html
The Law of Reflection.htm
Video Clip… (3:15)
Check Your Understanding…
– http://www.glenbrook.k12.il.us/gbssci/phys/Class/refln
/u13l1c.html
Reflection Activities
Symmetry and reflection...
How can you see more of your body in the
mirror?
Kaleidoscope Tesselations….
http://homepage.mac.com/efithian/Geomet
ry/Activity-11.html
Light Interacts With Matter
Refraction is the bending of waves caused
by a change in their speed. It is a type of
reflection.
– The amount of bending that occurs depends on
the speed of light in both materials.
– The greater the difference between the speeds of
light in two mediums, the more the light is bent as
it passes at an angle from one medium to another.
Light Refraction video clips
– Refraction.asf
– Wave_Refraction.asf
– chp6688_300k.asx
– Refracted_Light__Prisms.asf
Light Interacts With Matter
In order for you to see an object, it must reflect some
light. The type of matter in an object determines the
amount of light it absorbs and reflects.
– Opaque materials absorb or reflect all light and you cannot
see objects through them. (curtains, tables, walls)
– Transparent materials allow light to pass through and you
can clearly see objects through them. (glass)
– Translucent materials allow light to pass through but you
cannot clearly see objects through them because the light is
scattered. (frosted glass, waxed paper)
Eye Structure & Function
Eye Structure & Function
Video
How Light is Required to See
Light is a form of energy that moves
through space. It is constantly
streaming out from light sources in all
directions, traveling rapidly through
space and bouncing off most objects.
How the Eye Sees
Light enters the eye through a hole in the
cornea called the pupil and is focused on the
retina.
Light is then translated into nerve messages
that are carried by the optic nerve to the
brain.
How the Eye Sees
When an object reflects light waves it is
said to be illuminated.
In order to see these objects, the light
waves travel in a straight path and are
received by the eye.
How the Eye Sees Color
A red sheet of paper appears red because
red light is reflected off the paper, while all
other colored light (orange, yellow, green,
blue, indigo, violet) is absorbed by the
paper.
How Light is Required to See
Light behaves differently as it interacts
with different kinds of matter.
In order for one to see objects, light
must strike the object and then be
reflected from the object to their eyes.
Can You See In the Dark?
An object can be seen because of emitted
or reflected light.
In a “perfectly dark” room, an object
cannot be seen because no light is
reflected.
There is nothing in the benchmark
regarding lenses…..
Color
The following 3 screens show still pictures,
but look at how they seem to move due to
the colors that are used.
Explanation:
– Your eyes