2. How do you LIGHT UP your world ? 5.3 Light

3. 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?

4. 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.

5. How many sources of Light can you list and explain?

6. “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.

7. 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…

8. 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.

9. 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.

10. 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.

11. 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 “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

12. Don’t’ forget…longest waves (radio)..to shortest waves (cosmic)

13. Radio (Longest electromagnetic waves) Emitted by –Astronomical Objects –Radio Station Transmitters Detected by –Ground based radio telescopes –*If you turn on a radio,, it will convert the radio wave energy into sound energy.

14. Television Shorter than radio, also used to carry messages (pictures & sound) to our TV sets. *We can sense the TV waves around us with our televisions.

15. Microwave Emitted by: –Gas clouds collapsing into stars –Microwave Ovens –Radar Stations –Cell Phones Detected by –Microwave Telescopes –Food (heated) –Cell phones –Radar (systems)

16. Infrared (Heat or Thermal) Are you a source of infrared? YES you are! Emitted by –Sun and stars (Near) –TV Remote Controls –Food Warming Lights (Thermal) –*Everything at room temperature or above,=HEAT Detected by –Infrared Cameras –TVs, VCRs, –Your skin

17. Visible Each color is a different size wave. Red the longest & violet the shortest Emitted by –The sun and other astronomical objects –Laser pointers –Light bulbs Detected by –Cameras (film or digital) –Human eyes –Plants (red light) –Telescopes

18. Ultraviolet Sunburn / black light Emitted by –The sun –Tanning booths –Black light bulbs –UV lamps Detected by –Space based UV detectors –UV Cameras –Flying insects (flies)

19. X-ray Emitted by –Astronomical objects –X-ray machines –CAT scan machines –Older televisions –Radioactive minerals –Airport luggage scanners Detected by –Space based X-ray detectors –X-ray film –CCD detectors

20. Gamma Ray Emitted by –Radioactive materials –Exploding nuclear weapons –Gamma-ray bursts –Solar flares Detected by --Geiger counters –Gamma detectors and astronomical satellites –Medical imaging detectors

21. COSMIC Rays ( The highest energy waves and the deadliest) Cosmic rays come from deep space and can pass through the Earth.

22. Lewis Latimer African-American Lived from 1848-1928 Invented a long-lasting carbon filament that made the light bulb more useful. He also patented a threaded wooden socket for light bulbs and supervised the installation of electric streetlights in New York City, Philadelphia, Montreal, and London.

23. Isaac Newton English Lived from 1643-1727 Discovered that white light was not a simple entity, but splits into a range of colors When he passed white light through a glass prism, he noted that a spectrum of light was formed; particle theory of light Reflecting telescope

24. Anton van Leeuwenhoek Dutch; born in Holland Lived 1632-1723 Made over 500 simple microscopes Discovered bacteria, free-living and parasitic microscopic protists

25. Galileo Galilei Italian Lived from 1564-1642 Developed the refracting telescope Developed the first known example of the microscope

26. Robert Hooke English Lived from 1635-1703 Devised the compound microscope and illumination system Discovered plant cells Examined fossils with a microscope