Download Visible Light Waves

Welcome to a power point
presentation on LIGHT.
• We will investigate the following:
• 1. What is light?
• 2.What are some sources of light around us?
• 3. What are opaque, transparent, &
translucent
objects?
• 4. What is a light wave?
Light
• Our primary source of light is the sun.
• Light travels in straight lines at a speed of
186,000miles per second.
• *Light waves travel faster than sound waves!
• When light reaches an object, it is absorbed,
reflected, or passes through it.
Sensing Light
• Humans have two
light detectors.
• Do you know what
they are called?
How many sources of Light
can you list and explain?
• SUN=warms air,
water, and land.
• Fire=provides heat, light,
and cooking fuel.
• Lightning=
• Firefly=
• Flashlight=
• Light bulb=
• Laser beams=
• Optical
telephone
fibers=
*Traffic lights=
Can you answer this question?
1. Why does a person see a flash of
lightning before they hear thunder?
Because light travels faster than sound
What happens when light strikes an
object
• If light travels
through an object it is
=transparent
• If light is blocked by
an object it is=
opaque.
• If some light passes
through but not all it
is=translucent.
What happens when light
hits these objects?
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Glass of water
School bus window
Notebook paper
Waxed paper
Plastic wrap
Tissue paper
Cardboard
Textbook
Hand lens…
Transparent objects:
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The windows on a school bus,
A clear empty glass,
A clear window pane,
The lenses of some eyeglasses,
Clear plastic wrap,
The glass on a clock,
A hand lens,
ALL of these are transparent.
Yes, we can see through them
because light passes through
each of them.
Translucent objects
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Thin tissue paper,
Waxed paper,
Tinted car windows,
Frosted glass,
Clouds,
All of these materials
are translucent and
allow some light to
pass but the light
cannot be clearly
seen through.
Opaque objects:
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Heavy weight paper,
Cardboard
Aluminum foil,
Mirror, bricks, buildings,
Your eyelids and hands,
Solid wood door,
All of these objects are
opaque because light
cannot pass through them
at all.
• They cast a dark shadow.
What is light really?
Electromagnetic radiation waves
• The waves have highest
point is called “crests.”
• Waves also have low
points called “troughs.”
• *The distance from one
crest to the next crest is
called a “wavelength.”
• The distance from the
crest to the trough is the
amplitude
wavelength
*A Science Museum of VA:
Light Science Activity
What happens when light hits an
object?
• Reflects = bounces off an object at the
same angle.
• Refracts = light bends when it goes
through water.
• Absorbed= light enters an object and
stays in the object
Compare and contrast reflection
and refraction
Reflection
Refraction
Colors
• We have a famous name to help us
remember the colors we can see
•ROYGBIV
What Does ROYGBIV MEAN
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R= Red
O=Orange
Y= Yellow
G= Green
B= Blue
I= Indigo
V=Violet
Primary Colors
We can make every other color
from the primary colors
Notice the wavelength is long(Radio waves) and gets shorter (Gamma Rays)
Electromagnetic Spectrum
• Radio waves= used for communication
• Microwaves = used for communication
and heating food
• Infrared waves = used for heat
• Visible light = allows us to see color
• Ultraviolet waves = produce vitamin D
but too much is cancer
Electromagnetic Spectrum Continue
• X-Rays = used to see bones
• Gamma Rays = Help Cure Cancer