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.
There are seven members of electromagnetic family.
The order of electromagnetic waves in the spectrum is shown in the table below.
They are arranged in order of decreasing wavelength (and increasing frequency):
|Energy||Frequency||Wavelength||Radiation type||Typical wavelength in m||Typical use|
|Lowest||Lowest||Longest||Radio waves||1||Radio and television signals|
|Microwaves||1 x 10 -2||Cooking, mobile phones|
|Infrared||1 x 10-4||Heat transfer, night vision equipment, optical fibre communication|
|Visible light||4 x 10-7 to 7 x 10-7||Seeing, photography, optical fibre communication|
|Ultraviolet||1 x 10-8||Suntan, detecting forged bank notes|
|X-rays||1 x 10-10||Medical images of bones|
|Highest||Highest||Shortest||Gamma radiation||1 x 10-12||Killing cancer cells, sterilising medical equipment, killing bacteria to prolong shelf life of fruit|
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).