3.12 explain some of the uses of electromagnetic radiations, including
Radio waves: It is used in communicating information. This can be speech, radio and television, music and encoded messages like computer data, navigation signals and telephone conversations. The properties that make radio waves suitable for communicating are:
- Radio waves can travel quickly.
- Can code information.
- Can travel long distance through buildings and walls.
- It is not harmful.
Microwaves: Microwaves are used in microwave oven which cooks food more quickly than in normal oven. Microwaves are also used in communications. The waves pass easily through the Earth’s atmosphere and so are used to carry signals to orbiting satellites. From here, the signals are passed on to their destination. Messages sent to and from mobile phones are also carried by microwaves.
Infrared: Special cameras designed to detect infra-red waves can be used to create image even in the absence of visible light. Infra-red radiation is also used in remote controls for televisions, videos and stereo systems. Moreover it is used in heating materials like heater.
Visible light: The main use of visible light is to see. Visible light from lasers is used to read compact discs and barcodes. It can also be sent along optical fibres, so it can be used for communication or for looking into inaccessible places such as inside of the human body. Furthermore, it has uses in photography too.
Ultraviolet: Some chemicals glow when exposed to UV light. This property of UV light is used in security markers. The special ink is invisible in normal lights but becomes visible in UV light. UV light is also used in fluorescent lamps, to kill bacteria, to harden fillings and disco ‘black’ lights. Some insects can see into the ultraviolet part of spectrum and use this to navigate and to identify food sources.
X-rays: X-ray is used to take pictures of patient’s bone to determine any fracture. X-rays are also used in industry to check the internal structures of objects-for example: to look for cracks and faults in buildings or machinery- and at airport as part of the security checking procedure.
Gamma rays: They are used to sterillise medical instruments, to kill micro-organisms so that food will keep for longer and to treat cancer using radiotherapy.