Uses of EM waves

• What are radio waves used for?

  To transmit radio and terrestrial TV signals (terrestrial is received using an aerial). They are used because they can travel long distances before being absorbed. Longer wavelength radiowaves can also be spread out between hills (diffraction). Radiowaves can also reflect off a layer of charged particles in the atmosphere (ionosphere), this allows us to send radiowaves very long distances around the Earth.
• What are microwaves used for?

  Heating food because most foods contain a lot of water molecules which absorb the energy of microwaves. The energy causes the temperature of food to increase. They are also used to communicate with satellites in space because microwaves can pass through the Earth's atmosphere without being reflected or refracted.
• What is infrared used for?

  It is emitted by electrical heaters and is also used to cook food in ovens because the energy of infrared is easily absorbed by the surface of objects. Infrared is also used in infrared cameras.
• What is visible light used for?

  Used for communication using fibre optics. Optical fibres are very thin strands of glass, we can transmit pulses of light down these fibres and use these pulses to carry information. Optical fibres are used to carry telephone and cable TV signals. Because visible light has a short wavelength, it can carry a great deal of information.
• What is ultraviolet used for?

  Used for energy efficient lightbulbs, ultraviolet light is created inside the bulb and because ultraviolet has a short wavelength, it carries more energy than visible light. The energy of the ultraviolet is absorbed by the internal surface of the bulb and it is converted into visible light. This requires much less energy than a normal light bulb. Another use is in sun tanning, however, ultraviolet increases the risk of skin cancer and causes premature skin ageing.
• What are x-rays and gamma rays used for?

  Medical imaging, x-rays can be used to visualise broken bones and gamma rays are used to detect cancers. Both are very penetrative, meaning they easily pass through body tissue. X-rays are absorbed by bones which is why we can see them on x-ray images. They both can be used in medical treatments such as treating cancer.