Unit 1.8

• Types of waves

  • Longitudinal
  • Transverse
• Transverse wave

  • Vibrations at 90º to the direction of travel
• Longitudinal wave

  • Vibrations parallel to the direction of travel
• Refraction

  Change in direction and change in wavelength due to change in speed
• Reflection

  Wavelength does not change, angle from normal to wave when it hits object is the same as when it is reflected
• Satellite types

  • Geosynchronous
  • Geostationary
• Geosynchronous satellite

  • Returns to the same point once every 24 hours
• Geostationary satellite


  • Stays above the same point at all times
• Using geostationary satellites to send messages


  Signal must travel up to satellite and back, cannot travel straight from one satellite to another without returning to a station on the ground first
• Wave speed

  Distance (m) / Time (s)
• Wave speed

  Wavelength (m) x Frequency (Hz)
• Wave

  • Wavelength - length of one complete wave
  • Amplitude - maximum displacement
  • Frequency - number of waves in 1 second
• Parts of the electromagnetic spectrum

  • Radio waves
  • Microwaves
  • Infrared
  • Visible light
  • Ultraviolet
  • X rays
  • Gamma rays
• Electromagnetic spectrum

  • All parts transfer energy, all are transverse waves, all travel at same speed in vacuum (3 x 10^8 m/s), but have different properties and uses
• Optical density of water

  • Low optical density/deep water - higher speed, longer wavelength
  • High optical density/shallow water - slower, shorter wavelength