1. Electromagnetic Radiation Conceptual Physics    Ms O’Neill

2. Waves… a review  Most waves are either longitudinal or transverse.  Sound waves are longitudinal.  But all electromagnetic waves are transverse…

3. ? ?

4. Electromagnetic waves  Produced by the movement of electrically charged particles  Can travel in a “ vacuum ” (they do NOT need a medium  Travel at the speed of light  Also known as EM waves

5. Wave-particle Duality  Light can behave like a wave or like a particle  A “ particle ” of light is called a photon

7. Radio waves  Longest wavelength EM waves  Uses: TV broadcasting AM and FM broadcast radio Avalanche beacons Heart rate monitors Cell phone communication

8. Microwaves  Wavelengths from 1 mm- 1 m  Uses: Microwave ovens Bluetooth headsets Broadband Wireless Internet Radar GPS

9. Infrared Radiation  Wavelengths in between microwaves and visible light  Uses: Night vision goggles Remote controls Heat-seeking missiles

10. Visible light  Only type of EM wave able to be detected by the human eye  Violet is the highest frequency light  Red light is the lowest frequency light

11. Ultraviolet  Shorter wavelengths than visible light  Uses: Black lights Sterilizing medical equipment Water disinfection Security images on money

12. Ultraviolet (cont.) UVAUVB and UVC EnergyHighest of UV waves Lower than UVA Health risks  Extremely low risk for DNA damage  Can destroy Vitamin A in skin  Can cause DNA damage, leading to skin cancer  Responsible for sunburn

13. X-rays  Tiny wavelength, high energy waves  Uses: Medical imaging Airport security Inspecting industrial welds

14. X-rays absorbed reflected  Very little ordinary light can pass through skin. It’s either absorbed at the surface or reflected back….. more energy  To “see” inside we need a kind of “light” with more energy… Skin Ordinary Light X rays

15. Taking “X rays” The patient is placed in front of a source of X RAYS X ray Tube A photo graphic plate is placed on the other side of the patient Most of the X rays pass through the patient’s body…….

16. X-rays are absorbed by bone but can pass through skin and soft tissue bone Soft tissue Photographic plate X rays that are absorbed in the photographic plate cause chemical changes. These show as darkened areas when the plate is developed.

17. X-rays are also partly absorbed by some tissues in the body this creates a more subtle picture. bone Soft tissue Photographic plate

18.  What part of the body do these X Rays show? Answer : A knee

19. Gamma Rays  Gamma rays are given off by stars, and by some radioactive substances.  They are extremely high frequency waves, and carry a large amount of energy.  They pass through most materials, and are quite difficult to stop - you need lead or concrete in order to block them out.

20. Gamma Rays  Smallest wavelengths, highest energy EM waves  Uses Food irradiation Cancer treatment Treating wood flooring

21. The Songs!!!!  http://youtu.be/Ay2VFGDsxac http://youtu.be/Ay2VFGDsxac  Lazy Song vs The Electromagnetic Spectrum Song Lazy SongThe Electromagnetic Spectrum Song