The electromagnetic spectrum

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.

All known forms of waves from radio waves to gamma raysThe electromagnetic spectrum

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):

EnergyFrequencyWavelengthRadiation typeTypical wavelength in mTypical use
LowestLowestLongestRadio waves1Radio and television signals
Microwaves1 x 10 -2Cooking, mobile phones
Infrared1 x 10-4Heat transfer, night vision equipment, optical fibre communication
Visible light4 x 10-7 to 7 x 10-7Seeing, photography, optical fibre communication
Ultraviolet1 x 10-8Suntan, detecting forged bank notes
X-rays1 x 10-10Medical images of bones
HighestHighestShortestGamma radiation1 x 10-12Killing 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).

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The order of the electromagnetic spectrum