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1. COMMUNICATION

   • Mobile Phones
     • All send and receive microwaves.
     • Needs to be a line of sight between the phone and the receiver(phone mast).
   • Analogue
     • Continuously changing
   • Digital
     • Can only have two values (on or off, 1 or 0)
     • A series of pulses
     • Advantages
       • Any interference affecting the signal can be easily removed
       • Multiplexing, many different signals can be sent at once meaning you can send more information at one time.
   • Digital Audio Broadcasting Radio
     • Advantages
       • More stations available
       • Less chance of interference with other stations, so a clearer signal
     • Disadvantages
       • Not all areas of the UK are covered.
       • Sometimes the sound quality isn't as good as the sound is compressed.
   • Wireless
     • Communicating via electromagnetic waves
     • Wireless technology is portable and convenient

2. Seismic Waves

   • P-Waves
     • Can travel through solid and liquid parts of the Earth
     • Longitudinal Wave
   • S-Waves
     • These are slower than P-waves and are only able to travel through the solid parts of the Earth.
     • Transverse Wave

3. Ozone Layer and Ultraviolet Radiation

   • Ozone Layer is a thick layer of gas protecting us from the highest energy UV radiation.
   • CFCs break down Ozone layer.
     • CFCs banned under terms of 1987 Montreal Protocol and the hole in the ozone layer is gradually reducing in size.

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