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Electromagnetic waves-from slideshare

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Electromagnetic waves-from slideshare

  1. 1. ELECTROMAGNETIC WAVES SECONDARY 3 PHYSICS
  2. 2. WHAT ARE EM WAVES? <ul><li>Electromagnetic waves (EM waves for short) are waves that can travel in a vacuum. </li></ul><ul><li>These waves are created by the vibration of an electric charge. </li></ul>
  3. 3. Electromagnetic Spectrum <ul><li>It is a group of different electromagnetic waves. </li></ul><ul><li>There are 7 components in the spectrum. </li></ul>
  4. 4. Electromagnetic Spectrum <ul><li>Gamma rays </li></ul><ul><li>X – rays </li></ul><ul><li>Ultraviolet </li></ul><ul><li>Visible light </li></ul><ul><li>Infra-red </li></ul><ul><li>Microwaves </li></ul><ul><li>Radio waves </li></ul>Highest frequency Shortest wavelength Lowest frequency Longest wavelength
  5. 5. Uses of Gamma Rays <ul><li>Kill cancer cells </li></ul><ul><li>Study the nucleus in atoms </li></ul>
  6. 6. Uses of X-rays <ul><li>Take ‘pictures’ of bones in the body </li></ul><ul><li>Study the crystal structure of crystalline substances </li></ul><ul><li>Check for cracks in metal plates </li></ul>
  7. 7. Uses of Ultraviolet <ul><li>Detect counterfeit notes </li></ul><ul><li>Gives the clothes a ‘glow’ effect in discotheques </li></ul><ul><li>Sun-tanning </li></ul><ul><li>Sterilise medical equipment </li></ul>
  8. 8. Uses of Visible Light <ul><li>Enable us to see things </li></ul><ul><li>Photosynthesis in plants </li></ul>
  9. 9. Uses of Infra-red <ul><li>Heating </li></ul><ul><li>Haze photography </li></ul>
  10. 10. Uses of Microwaves <ul><li>Radar communication </li></ul><ul><li>Analysis of the molecular and atomic structure </li></ul><ul><li>Telephone communications </li></ul>
  11. 11. Uses of Radio Waves <ul><li>Radar communications </li></ul><ul><li>TV and radio broadcasting </li></ul>
  12. 12. Common Properties of EM Waves <ul><li>All transverse waves </li></ul><ul><li>All travel at the speed of light. (3 x 10 8 m/s) </li></ul><ul><li>Can travel through solid, liquid, gas and vacuum </li></ul><ul><li>Obey the laws of reflection and refraction </li></ul><ul><li>All can be absorbed and emitted by matter </li></ul><ul><li>The wave equation is applicable to all </li></ul>

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