Physics 1G

Physics 1G

1. Wireless technology uses electromagnetic radiation

2. The advantages of wireless technology are: no external/direct connection to a telephone needed, portable and convenient, allows access when on the move

3. The advantages of DAB radios are: more stations available, less interference with other broadcasts

4. The disadvantages of DAB radios are: poorer quality compared to FM, not all areas covered

5. Radiation used for communication is refracted and reflected and this can be an advantage or disadvantage for good reception

6. Common uses of wireless technology include: TV and radio, mobile phones and laptop computers

7. Radio waves (like light) exhibit total internal reflection

8. Key Processes

   • Infrared light: Information such as computer data and telephone calls can be converted into infrared signals and transmitted by optical fibres. Optical fibres are able to carry more information than an ordinary cable of the same thickness. In addition the signals they carry do not weaken so much over long distances. Television remote controls use infrared light to transmit coded signals to the television set in order to, for example, change channels or adjust the volume
   • Microwave radiation can be used to transmit signals such as mobile phone calls. Microwave transmitters and receivers on buildings and masts communicate with the mobile telephones which are in their range. Certain microwave radiation wavelengths pass through the Earth’s atmosphere and can be used to transmit information to and from satellites in orbit
   • Radio waves are used to transmit television and radio programmes. Longer wavelength radio waves are reflected from an electrically charged layer of the upper atmosphere. This means they can reach receivers that are not in the line of sight because of the curvature of the Earth’s surface
   • Analogue and digital: Before a sound or piece of information is transmitted, it is encoded in the transmitter in one of the ways described below - analogue or digital. The receiver must then decode the signal to produce a copy of the original information or sound. Analogue signals vary continuously in amplitude, frequency or both. Digital signals are a series of pulses with two states - on (shown by the symbol ‘1’) or off (shown by the symbol ‘0’). Digital signals carry more information per second than analogue signals and they maintain their quality better over long distances.