electromagnetic spectrum

• electromagnetic waves are a group of waves produced due to the combined oscillation of the electric & magnetic field
• N = L x F
• Waves:

  1. transverse
  2. same speed as light, 3.0 x 10^8 m/s
  3. different wavelength
  4. different frequency
  5. can be reflected, refracted, diffracted
• radio waves

  microwaves

  infrared

  visible light: ROYGBIF

  ultraviolet

  x ray

  gamma ray
• Uses of the electromagnetic spectrum

  1. radio waves - RFID & TV transmissions
  2. microwaves - mobile & microwave ovens
  3. infrared - electric grills & thermal imaging
  4. visible light - vision & photographs
  5. ultraviolet - sterilizing water & tanning booths
  6. x rays - medical scanning & security scanners
  7. gamma ray/y rays - sterilizing equipment & radio therapy
• the harmful effects of excessive exposure of electromagnetic radiation on humans:

  1. microwave: internal heating of body cells
  2. infrared: skin burns
  3. UV: damage to surface cells of eyes leading to skin cancer & eye conditions
  4. x-ray & y-ray: mutation or damage to cells in the body
• many important systems of communication rely on electromagentic radiation including:

  1. mobiles
  2. blue tooth (uses radio waves)
  3. optical fiber
• transmission:

  1. analogue

  • signals which vary continuously in frequency & amplitude

  2. digital

  • signals that consist pules which are on or off
• the analogue signals are converted to digital signals using converters "en coders"
• sound waves can be transmitted as analogue or digital
• pros of digital:

  1. faster
  2. more accurate
  3. increases rate of transmission
  4. increased range due to accurate signal