Transcript Light - SCHOOLinSITES

Light
Table of Contents
Light and Color
Reflection and Mirrors
Refraction and Lenses
Seeing Light
Using Light
Light - Light and Color
When Light Strikes an Object
When light strikes an object, the
light can be reflected, transmitted,
or absorbed.
Light - Light and Color
The Color of Objects
The color of an opaque object is the color of the light it
reflects.
Light - Light and Color
The Color of Objects
The color of a transparent or translucent object is the color of
the light it transmits.
Light - Light and Color
Combining Colors
As pigments are added together, fewer colors of light are
reflected and more are absorbed.
Light - Light and Color
Building Vocabulary
Using a word in a sentence helps you think about how best
to explain the word. After you read the section, carefully note
the definition of each Key Term. Also note other details in the
paragraph that contain the definition. Use all this information
to write a sentence for each Key Term.
Key Terms:
transparent
primary
colors
material
translucentcolor
secondary
material
opaque materialcolors
complementary
pigment
Examples:
Three
A
transparent
colors that
material
can combine
transmits
to make
most any
of the
other
lightcolor
that
strikes
are
called
it. primary colors.
A translucent
Two
primary colors
material
combine
scatters
in equal
light amounts
as it passes
to
through. a secondary color.
produce
An opaque
Any
two colors
material
that combine
reflects to
or form
absorbs
white
alllight
of the
arelight
that strikes
called
complementary
it.
colors.
Pigments are colored substances that are used to
color other materials.
Light - Light and Color
Color
Click the Video button to watch a movie about color.
Light - Light and Color
Links on Colors
Click the SciLinks button for links on colors.
Light
End of Section:
Light and Color
Light - Reflection and Mirrors
Reflection of Light Rays
The two ways in which a surface can reflect light are regular
reflection and diffuse reflection.
Light - Reflection and Mirrors
Concave Mirrors
A mirror with a surface that curves inward like the inside of a
bowl is a concave mirror.
Light - Reflection and Mirrors
Concave Mirrors
Ray diagrams show where an image forms and the size of
the image. The steps below show how to draw a ray
diagram.
Light - Reflection and Mirrors
Concave Mirrors
Concave mirrors can form either virtual images or real
images.
Light - Reflection and Mirrors
Convex Mirrors
A mirror with a surface that curves outward is called a
convex mirror.
Light - Reflection and Mirrors
Mirrors Activity
Click the Active Art button to open a browser window and
access Active Art about mirrors.
Light - Reflection and Mirrors
Comparing and Contrasting
As you read, compare and contrast concave and convex
mirrors in a Venn diagram like the one below. Write the
similarities in the space where the circles overlap and the
differences on the left and right sides.
Concave Mirror
Convex Mirror
Real images
Enlarged
images
Curves inward
Virtual
images
Reduced
images
Curves
outward
Light
End of Section:
Reflection and
Mirrors
Light - Refraction and Lenses
Bending Light
The index of refraction of a
medium is a measure of how
much light bends as it travels
from air into the medium. The
table shows the index of
refraction of some common
mediums.
Light - Refraction and Lenses
Bending Light
Interpreting Data:
Which medium causes the
greatest change in the
direction of a light ray?
Diamond causes the greatest
change in the direction of a
light ray traveling from air.
Light - Refraction and Lenses
Bending Light
Interpreting Data:
According to the table, which
tends to bend light more:
solids or liquids?
According to the graph, most
solids bend light more than
liquids do (quartz is an
exception).
Light - Refraction and Lenses
Bending Light
Predicting:
Would you expect light to
bend if it entered corn oil at
an angle after traveling
through glycerol? Explain.
You would not expect light to
bend if it entered corn oil at
an angle after traveling
through glycerol, because
corn oil and glycerol have the
same value for the index of
refraction.
Light - Refraction and Lenses
Refraction of Light
When light rays enter a medium at an angle, the change in
speed causes the rays to bend or change direction.
Light - Refraction and Lenses
Lenses
A lens is a curved piece of glass or other transparent
material.
Light - Refraction and Lenses
Lenses
An object’s position relative to the focal point determines
whether a convex lens forms a real image or a virtual image.
Light - Refraction and Lenses
Lenses
A concave lens can produce only virtual images because
parallel light rays passing through the lens never meet.
Light - Refraction and Lenses
Lenses Activity
Click the Active Art button to open a browser window and
access Active Art about lenses.
Light - Refraction and Lenses
Asking Questions
Before you read, preview the red headings. In a graphic
organizer like the one below, ask a what, when, where, or
how question for each heading. As you read, write answers
to your questions.
Question
Answer
When does refraction
occur?
When light rays enter a
medium at an angle
What are the types of
lenses?
Concave and convex
lenses
Light
End of Section:
Refraction and
Lenses
Light - Seeing Light
Correcting Vision
Concave lenses are used to correct nearsightedness.
Convex lenses are used to correct farsightedness.
Light - Seeing Light
Sequencing
Sequence is the order in which the steps in a process occur.
As you read, make a flowchart that shows how you see
objects. Put the steps of the process in separate boxes in the
order in which they occur.
How You See Objects
Light enters the eye.
Light focuses on the retina.
An image forms.
Rods and cones send signals to the brain.
Light - Seeing Light
More on Eyesight
Click the PHSchool.com button for an activity about eyesight.
Light
End of Section:
Seeing Light
Light - Using Light
Optical Instruments
A telescope forms enlarged images of distant objects.
Telescopes use lenses or mirrors to collect and focus light
from distant objects.
Light - Using Light
Optical Instruments
A microscope uses a combination of lenses to produce and
magnify an image.
Light - Using Light
Optical Instruments
The lens of the camera focuses light to form a real, upsidedown image on film in the back of the camera.
Light - Using Light
Lasers
Laser light consists of light waves that all have
the same wavelength, or color. The waves are
coherent, or in step.
Light - Using Light
Optical Fibers
The floodlight in the swimming pool gives off light rays that
travel to the surface. If the angle of incidence is great
enough, a light ray is completely reflected back into the
water. This complete reflection of light by the inside surface
of a medium is called total internal reflection.
Light - Using Light
Optical Fibers
Optical fibers can carry a laser
beam for long distances
because the beam stays totally
inside the fiber as it travels.
Light - Using Light
Building Vocabulary
A definition states the meaning of a word or phrase by telling
about its most important feature or function. Carefully read
the definition of each Key Term. Then write a definition of
each Key Term in your own words.
Key Terms:
Examples:
microscope
total
internal reflection
telescope
The
A
microscope
total internal
is device
an
reflection
instrument
is the
that
complete
formsorenlarged
reflection
telescope
is a
that uses
lenses
mirrors
to
images
of
light and
by
of the
tiny
inside
objects
usingdistant
lenses.
of a medium.
collect
focus
lightsurface
from
objects.
camera
refracting telescope
A camera
is atelescope
device that
lenses that
to focus
refracting
is uses
a telescope
useslight on
film
to record
convex
lensesan
toimage.
focus light.
A
is a device
produces
intense beam
of
Anlaser
objective
is thethat
large
lens in aan
telescope
or
coherent
light.
microscope
that gathers and focuses light.
A
three-dimensional
photograph
Anhologram
eyepiece isisathe
lens near the eye
in a telescope or
created
by athat
laser.
microscope
magnifies the image.
An
optical fiber
is a strand
glass orthat
plastic
that
A reflecting
telescope
is a of
telescope
uses
a can
carry
lightmirror
long distances.
concave
to gather light.
laser
objective
hologram
eyepiece
optical
fiber
reflecting
telescope
Light - Using Light
Links on Lasers
Click the SciLinks button for links on lasers.
Light
End of Section:
Using Light
Light
Graphic Organizer
Type of Mirror
Effect on Light Rays
Type of Image
Plane
Regular reflection
Virtual
Concave
Converge
Real or virtual
Convex
Spread out
Virtual
Type of lens
Effect on Light Rays
Type of Image
Convex
Converge
Real or virtual
Concave
Spread out
Virtual
Light
End of Section:
Graphic Organizer