2. 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, and translucent
objects?
• 4. What is a light wave?
3. 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!
• Light energy from the sun travels through space,
reaches earth, and some of it turns to heat energy
and warms the earth’s air.
• Light from the sun also travels to the cells of green
plants (producers) and is stored as energy.
• When light reaches an object, it is absorbed,
reflected, or passes through it.
4. Sensing Light
• Humans have two light
detectors.
• Do you know what
they are called?
5. 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=
*
6. Can you answer these 6th grade
questions?
• 1. A person will see a flash of lightning before they
hear the thunder that goes with it because?
• 2.Can you draw a long wavelength and a short
wavelength next to it?
• 3. Can you contrast objects that are transparent,
translucent, and opaque?
7. “Just Passing Through:”
What happens when light strikes glass? Or
waxed paper? Or a book?
• If light travels through an
object it is =transparent
• If light is blocked by an
object and a dark shadow
is cast it is= opaque.
• If some light passes
through but not all and a
light shadow is present it
is=translucent.
8. What happens when light
hits these objects?
• Glass of water
• School bus window
• Notebook paper
• Waxed paper
• Plastic wrap
• Tissue paper
• Cardboard
• Textbook
• Hand lens…
9. Transparent objects:
• 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,
• Colored glass…
• ALL of these are transparent. Yes,
we can see through them because
light passes through each of them.
10. Translucent objects
• 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.
11. Opaque objects:
• 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.
12. Let’s find out how light travels?
• Simple Activity: 1 working flashlight
• 1. Shine a flashlight on a wall.
• 2. Does light from the flashlight reach the
wall? How do you know?
• 3. What evidence do you have showing light
travels in a straight line?
• 4.Move closer with the flashlight. Any
changes?
13. What is light really?
Electromagnetic radiation waves
• The waves have high points
called “crests.” wavelength
• Waves also have low points
called “troughs.”
• *The distance from one
crest to the next crest is
called a “wavelength.”
• *The number of waves
passing a given point in
one second is called the
“frequency.”
