How do you LIGHT Up your world ?

1. How do you LIGHT Up your world ?

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, & 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 186,000 miles per second. • *Light waves travel fasterthan 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= *Trafficlights=

6. 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?

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.Record answers in your science journal • 5.Move closer with the flashlight. • Any changes? *Write a story about light.

13. 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

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