Electromagnetic Waves

• electromagnetic waves

  are transverse waves that travel through a vacuum at the speed of light
• EM spectrum

  A) radiowaves

  B) microwaves

  C) infrared radiation

  D) visible light

  E) ultraviolet

  F) x-rays

  G) gamma-rays

  
• PRACTICAL - INVESTIGATING LIGHT

  1. place a transparent rectangular block on paper and trace around it
  2. using a ray box shine a light on one side of block and trace angle of incidence
  3. remove block and join up incident ray and emerging point to show reflected ray
  4. draw a normal line
  5. using a protractor measure angle line between angle of incidence and normal then between angle of reflection and normal
  6. repeat experiment with different rectangular boxes
• EM waves are made up of oscillating electric and magnetic fields
• uses of EM waves

  • radios
  • microwaves
  • infrared radiation
  • visible light
  • UV radiation
  • x-rays
  • gamma rays
• radios

  • made by oscillating charges
  • mainly used for communication and transmission
  • wavelength - 10^3m
  • radio - 10^3Hz
• microwaves

  • used by satellites and microwave ovens
  • wavelength - 1m
  • frequency - 10^6Hz
• infrared radiation

  • used to increase or monitor temperature
  • hazard - burns
  • wavelength - 10^-3m
  • frequency - 10^12Hz
• visible light

  • used by fibre-optic cables to transmit data
  • wavelength - 10^-5m
  • frequency - 10^14Hz
• UV radiation

  • used for tanning beds, killing flies and sterilisation
  • hazards - mildly ionising and give skin cancer
  • wavelength - 10^-7
  • frequency - 10^15Hz
• x-rays

  • used in medicine
  • hazards - ionising
  • wavelength - 10^-8m
  • frequency - 10^19Hz
• gamma rays

  • used in medicine
  • hazards - dangerously ionising
  • wavelength - 10^-9
  • frequency - 10^23
• non-ionising EM spectrum

  • radiowaves
  • microwaves
  • infrared radiation
  • visible light
• ionising EM spectrum

  • UV radiation
  • x-rays
  • gamma rays