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, & 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

186,000 miles 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 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.What scientific tools are used to study light?

• 4. 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.Record answers in your science journal

• 5.Move closer with the flashlight.

• Any changes? *Write a story about light.

What is light really?

• Light waves are three dimensional.

• Light waves vibrate in all planes around a center line.

• The waves have high points called “peaks.”

• Waves also have low points called “valleys.”

• *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

Notice the wavelength is long(Radio waves) and gets shorter (Gamma Rays)