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  • Waves
    • Microwaves
      • Wavelengths: 1mm-30cm
      • Cooking: Water and fat molecules vibrate more, kintetic energy increases, conduction
      • Communicating
        • The transmitter and reciever-line of sight
          • Aerials normally on high buildings
        • Satellites
          • The signal form earth is recieved, amplified, re-transmitted back to earth from the satellites
          • They work becasues there's no onstructions in space
        • Signal strength for mobile phones can change a lot over short distances
          • Don't show much diffraction
          • Adverse weather and water scatters signals
          • The curvature of earth limits line of sight so transmitters have to be high up or close together
          • Interfere
      • Pass through ionsphere
    • Radio waves
      • Refracted and reflected by earth atmosphere
        • Less refraction at higher frequencies
      • Interference is reduced if digital signals are used
        • DAB eliminates interference
      • Same freq can be used by other radio stations
        • too far away and wont interfer
        • But in unusual weather conditions waves can travel further and interfer
      • Radio waves are refelcted from the earth ionsphere- total internal reflection
        • Water reflects, land doesnt
        • Recieved from aerials not in line of sight
      • Problems with communication
        • Diffracted when they meet obstruction
        • Slightly divergent
    • EArthquake waves
      • P waves longitudinal pressure waves. Speed 5km/s and 8km/s. Travel through SOLIDS and LIQUIDS
      • S-waves are transverse, 3km/s-5.5km/s. Can only pass through SOLIDS


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