light
TRANSCRIPT
How do you LIGHT Up
your world ?
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?
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.
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 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?
“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.
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…
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.
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.
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.
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?
What is light really? Electromagnetic radiation waves
• The waves have high points called “crests.”
• 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.”
wavelength