1. Light: Electromagnetic Radiation

2. Important Vocabulary  Electromagnetic radiation  Photon  Radio wave  Microwave  Infrared radiation  Visible radiation  Ultraviolet radiation  X ray  Gamma ray

3.  Fold each piece of construction paper to form a sleeve.  Insert a thermometer into each sleeve.  Place it 25 cm from a light source, record temperature  Wait 10 minutes, record temperature of each sleeve again Color25 cm (start)25 cm (10 minutes after)

4. Color25 cm (start)25 cm (10 minutes after) Black Yellow Orange Blue

5. Electromagnetic Radiation  Transverse waves produced by electrically charged particles  They radiate from particles  The transfer of energy by electromagnetic waves is called radiation  They DO NOT need a medium to transfer energy  Travel faster than sound or water waves

6. Electromagnetic Radiation  Travel at the same speed in a vacuum, but frequencies and wavelengths differ  Shorter the wavelength the __________ the frequency  Radiation carries energy and momentum  Light is composed of tiny particles called photons  Photons with the highest energy correspond to light with the highest frequency  High energy photons can damage matter

7. Radio Waves  When you tune a radio to a station, you are adjusting to respond to radio waves of a certain frequency  Long wavelengths and low frequencies  High / Low photon energy  Used in television, cellular telephones and cordless telephones

8. Radio Waves  Radio waves with the highest frequency and energy are called microwaves  Used in communications and speedy cooking  Microwaves transfer energy to the water molecules that are inside food, causing them to vibrate and move faster  The result is the kinetic energy and temperature of the water molecules increase

9. Infrared Radiation  Infrared Radiation has a wavelength slightly longer than visible light  Think of a nice sunny day, what happens to your skin? What happens when the clouds cover the sun?  Warm objects give off more infrared radiation than cool objects  Measurements of the body’s emission of infrared radiation help doctors make medical diagnosis

10. Visible Radiation – light  The only part of the electromagnetic spectrum that you can see  Light can also cause chemical reactions to occur such a as:   Can stimulate decomposition reactions of materials

11. Ultraviolet Radiation  Why do you wear sunglasses or sunscreen in strong sunlight?  Ultraviolet radiation has a higher frequency than visible light  Photons are more energetic and have greater power than photons of visible light  Exposure to UV rays produce vitamin D, kill bacteria, and sterilize surgical instruments  Overexposure can lead to damaged skin, cancer  Ozone protects us from UV rays

12. Ozone  Earth’s natural filter  Blocks most of the sun’s UV rays  It is a form of oxygen where oxygen atoms cobmine to make each ozone molecule  Reduction in the ozone = an increase in UV rays  Chemicals break down ozone

13. X Rays

14. Gamma Rays

15. Homework p. 535 #1-3