Lesson 3


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Lesson 3

  1. 1. How is being inside a microwave oven like standing in a city street?
  2. 2. These places are bathed in electromagnetic radiation (the oven in microwaves, the street in radio waves from TV and radio stations, microwaves from mobile phones, UV from the Sun etc). How is being inside a microwave oven like standing in a city street?
  3. 3. Lesson 3 Hot Stuff
  4. 4. You will be successful if you can: <ul><li>Describe how E-M radiation transfers energy </li></ul><ul><li>Explain ionisation </li></ul><ul><li>Explain how E-M radiation can cause damage to living tissue. </li></ul>
  5. 5. At one end of the electromagnetic spectrum are radio radiations. Radio photons carry little energy. radio VHF (radio) radio VLF radio UHF (TV) radio (AM radio)
  6. 6. Some types of electromagnetic radiation, if intense enough, have a noticeable warming effect.
  7. 7. Microwave radiation can be good at heating anything with water in it.
  8. 8. <ul><li>Electromagnetic waves transfers energy from source to absorber, and often the only effect is heating of the absorber. </li></ul>
  9. 9. Gamma rays, X-rays, and UV are radiations that have the most energetic photons. UV X-ray gamma rays
  10. 10. Radiation is emitted and absorbed as photons. UV transfers energy to skin, but heating is not the only effect
  11. 11. All types of electromagnetic radiation travel as photons. They are packets of energy. absorbing molecule from source
  12. 12. Ionization happens when a photon with enough energy hits an atom or molecule inside a material. An individual collision between a photon and an atom can ionize the atom, if the photon is sufficiently energetic
  13. 13. UV radiation, X-rays, and gamma rays transfer energy to material in local and dramatic ways.
  14. 14. Ionisation When radiation collides with neutral atoms or molecules it alters their structure by knocking off electrons. This will leave behind IONS – this is called IONISING RADIATION. High energy radiation Electron
  15. 15. Ionisation Some types of radiation are dangerous because they “ionises” atoms – in other words, it turns them into ions by “knocking off” electrons: Ionisation causes cells in living tissue to mutate, usually causing cancer. High doses can destroy cells completely, causing radiation sickness. Radiation
  16. 16. Only radiations with high-energy photons can cause ionization. radio VLF radio VHF (radio) microwave infrared UV X-ray gamma rays cosmic rays radio UHF (TV) radio (AM radio) ionizing radiation non-ionizing radiation visible spectrum
  17. 17. Ionisation to you <ul><li>Summarise ionisation in a sentence </li></ul><ul><li>How could you improve the ionisation role play we did last lesson? </li></ul>