The electromagnetic spectrum is a large family of waves and there are uses for all of its members. Here, you will find out about just 5 of the important uses of electromagnetic radiation that you need to know for your GCSE.
What is Electromagnetic Radiation?
Electromagnetic radiation is the term given to a family of transverse waves that propagate via vibrations in the electric and magnetic fields that extend throughout the universe. They do not need a medium (substance) to travel so they can pass trough empty space. Some of them can also go through solids, liquids and gases which makes them incredibly useful.
1. Radio and Television
Most of you will have at least one radio and probably a television in your house but have you ever stopped to think about how the programmes get from the broadcaster to your TV or radio? You have? Excellent, then you will probably know that it is electromagnetic radiation from the long wavelength end of the spectrum that is used – radio waves.
The broadcasters change the properties of the radio waves in order to transmit the signals. These are decoded by your radio or TV for you to enjoy. TV signals and an increasing number of radio signals are transmitted digitally which gives much better quality than the old analogue signals. Before the age of digital TV and radio, as the waves went from the transmitter to your radio or television, other signals, atmospheric conditions and radiation from space disturbed it, creating ‘noise’. This noise meant that when you listened or watched, the quality of what you received was a lot worse than what had originally been sent out. Digital signals, carried by radio waves also pick up noise but it is a whole lot easier to detect it and filter it out.
2. Mobile Telephones
Mobile telephones are receivers and transmitters of microwave radiation. These are shorter wavelength and higher frequency than radio waves which has caused some people to be very concerned about health issues. Whereas radio waves can actually bend round and over large objects like hills (look up ‘diffraction of radio waves‘ if you want to know more) and can even go through buildings, microwaves don’t bend so easily and can only get through fairly thin walls. This means that you can only use your mobile if you are in a direct line with a mobile telephone mast and why they sometimes don’t work so well inside buildings.
3. Broadband InternetDuring the 1970’s, fibre optic systems were developed. These use light at infra-red wavelengths to carry data through cables made from very fine glass fibres. Such systems can carry huge amounts of data and were originally used for carrying telephone signals. Further development of fibre optic cables and technology has meant that infra-red can now be used to deliver extremely fast broadband to homes and businesses. The reason fibre optics is so efficient is that the light is contained within the fibres by total internal reflection, only a very tiny proportion is absorbed by imperfections in the tiny glass fibre.
4. CAT scanners
A CAT (Computerised Axial Tomography) scanner uses X-rays to look inside the body and generates detailed 3D pictures of the person being scanned. Can you pick out the advantages and disadvantages of CAT scans compared to normal X-rays?
- The technique utilises the power of computers to generate 3D images
- CAT scans are a source of ionising radiation and can cause cancer
- A CAT scanner uses several beams of X-rays producing more detail than an ordinary single beam X-ray
- CAT scanners can create detailed images of soft tissues, organs, blood vessels, and the brain
CAT scanners are sometimes simply referred to as CT scanners.
5. Surgical Instrument Sterilisation
At the high energy end of the electromagnetic spectrum is Gamma radiation. This is associated with radioactivity and is therefore always thought of as being highly dangerous. That is indeed true, however, it is useful where micro-organisms need to be eliminated. When carrying out operations in hospitals, the equipment needs to be completely free of any micro-organisms. This extreme cleanliness can be achieved by using gamma rays which will kill any bacteria and fungus and destroy any viruses that mah be found on surgical instruments.
There are of course many other uses for this versatile family of waves, for example, they have been used to reveal some of the answers to the mysteries of the universe, they are used to help to preserve food for longer, they are used to change channels on the TV and to help Dentists with their work.