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Electromagnetic Radiation

Electromagnetic Radiation. Conceptual Physics       J. Beauchemin 2009. Waves… a review. Most waves are either longitudinal or transverse. Sound waves are longitudinal. But all electromagnetic waves are transverse…. ?. ?.

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Electromagnetic Radiation

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  1. Electromagnetic Radiation Conceptual Physics  J. Beauchemin 2009

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

  3. ? ?

  4. When an electric field changes, so does the magnetic field. The changing magnetic field causes the electric field to change. When one field vibrates—so does the other. • RESULT-An electromagnetic wave. Click here Animation: Interaction of vibrating charges

  5. 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

  6. EM Spectrum Defined • Electromagnetic Spectrum—name for the range of electromagnetic waves when placed in order of increasing frequency, decreasing wavelength.

  7. B. Waves of the Electromagnetic Spectrum • Click here (Animation—Size of EMwaves)

  8. Radio waves • Longest wavelength EM waves • Uses: • TV broadcasting • AM and FM broadcast radio • Heart rate monitors • Cell phone communication

  9. Radio Transmission • A transmitter produces an electrical current. This energy is transmitted to an antenna. • The antenna produces electromagnetic waves (radio waves) that get sent through space. • The receiving antenna picks up and converts the radio waves into sound that we can hear

  10. AM vs FM

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

  12. Microwaves • Microwaves are sent through and “excite” the atoms that make up food, which results in heat energy.

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

  14. IR • Anything that emits heat will emit IR. So all of us are emitting Infrared radiation right now! • IR can be used to “see” heat

  15. 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

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

  17. UV Health Risks • Skin cancer • Cataracts • Suppression of the immune system • Premature aging of the skin

  18. When are UV rays the strongest? • UV rays tend to be stronger in the summer and at noon, when the sun is highest in the sky. The UV Index forecasts the strength of the sun’s harmful rays. The higher the number, the greater the chance of sun damage.

  19. Ultraviolet (cont.)

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

  21. X-rays work because x-rays pass through soft tissue, but not hard tissues like bone. The x-rays that pass through the soft tissue are detected and the image is then generated.

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

  23. All stars produce gamma rays, but massive stars produce the most! • Gamma ray bursts are produces when a star explodes or goes supernova • Gamma rays from the sun do not reach earth because our atmosphere filters them out!

  24. Using the EM waves to view the Sun Animation—View a Galaxy at different wavelengths

  25. Image credits • http://www.antonine-education.co.uk/New_items/MUS/images/Making6.gif • http://www.geocities.com/researchtriangle/campus/6791/einstein12.jpg • http://abyss.uoregon.edu/~js/glossary/wave_particle.html • http://www.astro.princeton.edu/~gk/A402/electromagnetic_spectrum.jpg • http://science.hq.nasa.gov/kids/imagers/ems/radio.html • http://www.nentjes.info/Palace/radio-6.gif • http://www.mobilewhack.com/motorola-h12-bluetooth-headset.jpg • http://www.stuffintheair.com/radar-real-time-weather.html • http://www.imaging1.com/gallery/images/AV%20Night%20vision%20goggles.jpg • http://www.global-b2b-network.com/direct/dbimage/50329753/Study_Remote_Control.jpg • http://www.georgiaprismaward.com/The_Prism_Story_files/PRISM%20brand%20imagemed.jpg • http://science.hq.nasa.gov/kids/imagers/ems/uv.html

  26. Image Credits • http://farm3.static.flickr.com/2385/2381723771_12548f4bd1.jpg?v=1217429879 • http://intamod.com.au/images/uv2.JPG • http://science.hq.nasa.gov/kids/imagers/ems/xrays.html • http://www.sciencelearn.org.nz/var/sciencelearn/storage/images/contexts/see_through_body/sci_media/neck_x_ray/17945-5-eng-NZ/neck_x_ray_full_size_portrait.jpg • http://www.epinion.eu/wordpress/wp-content/uploads/2008/05/airport-security1.jpg • http://science.hq.nasa.gov/kids/imagers/ems/gamma.html • http://www.aboutnuclear.org/print.cgi?fC=Food • http://www.roswellpark.org/files/1_2_1/brain_spinal/gamma%20knife%204c.jpg

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