Electromagnetic Spectrum
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.