The electromagnetic spectrum is a continuous range of wavelengths. The types of radiation that occur in different parts of the spectrum have different uses and dangers - depending on their wavelength and frequency.
The order of electromagnetic waves in the spectrum is shown in the table.
|Energy||Frequency||Wavelength||Radiation type||Typical use|
|Lowest||Lowest||Longest||Radio waves||Television signals|
|Microwaves||Cooking, mobile phones|
|Infrared||Optical fibre communication|
|Ultraviolet||Detecting forged bank notes|
|X-rays||Medical images of bones|
|Highest||Highest||Shortest||Gamma radiation||Killing cancer cells|
Radio waves have the lowest frequencies and longest wavelengths, while gamma waves have the highest frequencies and shortest wavelengths.
All of these waves travel at the same speed in free space, which is the speed of light or about 300,000,000 m/s (metres per second).