Summary of electromagnetic spectrum
All electromagnetic waves can travel through vacuum. They all travel at the speed of 3 X 10^8 m/s in vacuum and very close to this value through air.
In other materials however, they travel a bit slower. Each selection of the electromagnetic spectrum has its own uses and features:
|Region||Frequency Range (Hz)||Wavelength Range (M)||Applications|
|Radio||105 – 1010||104 – 10-2||Electromagnetic oscillations produced by electric circuits; Received by aerial and used in communication|
|Microwave||1010 – 1011||10-2 – 10-3||Used for rapid heating in microwave; Used to communicate with satellites i.e. mobile phones|
|Infra-red||1011 – 1014||10-3 – 10-6||All hot objects produce infrared; Used for night goggles, burglar alarms, etc. (since all humans emit infra-red)|
|Visible||1014||10-7||Produced by very hot objects such as the sun; Detected by the eye; Used in optical fibres communication|
|Ultraviolet||1015 -1017||10-7 – 10-9||Causes fluorescence in some materials; Uses with sunbeds to produce sun tan|
|X-Radiation||1017 – 1019||10-9 – 10-11||Blackens photographic film; Used in diagnosis (X-Ray scan); Dangerous in high doses|
|Gamma Radiation||1019 – 1020||10-11 – 10-14||Produced in nuclei of radioactive elements; Used in medical diagnosis but dangerous in high dosage|
The higher the frequency, the higher the energy of the radiation. Therefore, radio waves have the lowest energy and gamma radiation has the highest energy within the spectrum.