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Electromagnetic Waves
1. Electromagnetic waves originate from accelerating charges.
2. They consist of electric and magnetic fields at right angles to each other.
3. They can travel through a vacuum.
4. They can be diffracted, proving they are waves.
5. They also display interference, further proving their wave nature.
6. They can be polarized, proving they are transverse.
7. Their speed through a vacuum is 3x108m.s-1.
The Electromagnetic Regions
(from highest to lowest frequency)

1. Gamma Rays
f = 1020 Hz to 1024 Hz

  • emitted by radio-active elements
  • very penetrative
  • very dangerous

2. X-Rays
f = 1015 Hz to 1019 Hz

  • high penetrative powers
  • used in medical field to photograph bones
  • harmful if used in excess

3. Ultra-Violet
f = 1015 Hz to 1018 Hz

  • harmful
  • UV protection required

4. Visible Light
f = 1014 Hz

  • violet
  • indigo
  • blue
  • green
  • yellow
  • orange
  • red

5. Infra-Red
f = 1012 Hz to 1014 Hz

  • heat waves

6. Microwave Radar
f = 1011 Hz

  • cooking (microwave ovens)
  • transmission of data over long distances

7. Radio Waves
f = 100 Hz to 1011 Hz

  • TV
  • FM (frequency modulation)
  • Short Wave
  • AM (amplitude modulation)
  • Long Wave

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