Parts of the electromagnetic spectrum
A large family of waves, each with a different wavelengthThe length of a single wave, measured from one wave peak to the next. range is called the electromagnetic spectrumThe different types of electromagnetic radiation, arranged in order of frequency or wavelength. (sometimes shortened to the EM spectrum). These waves all travel at the speed of light (300,000,000 metres per second) in a vacuum.
The table below lists the different radiations in the electromagnetic spectrum and shows some information about each radiation.
| Type of wave | Typical source | Example of detector | Approximate wavelength | Typical users | Dangers of over exposure |
| Radio: LW | electronic circuits, stars and space | aerial and electronic circuit | 1km | communications, radio, TV | safe (unless very concentrated) |
| Radio: MW | electronic circuits, stars and space | aerial and electronic circuit | 100m | communications, radio, TV | safe (unless very concentrated) |
| Radio: VHF | electronic circuits, stars and space | aerial and electronic circuit | 1m | communications, radio, TV | safe (unless very concentrated) |
| Microwaves | electronic circuits, cool objects | aerial and electronic circuit | 1cm (10-2m) | communications satellites, telephony, heating water and food | burning, if concentrated |
| Infra red (IR) | electronic devices, warm objects, sun | electronic detectors, special photographic film, blackened thermometer | 0.1mm (10-4m) | magic eyes in security lighting, remote control (eg TV) | burning, if concentrated |
| Light; Red, Orange, Yellow, Green, Blue, Indigo, Violet | electronic devices (LED), hot objects, sun | eye, photographic film, electronic devices (eg, LDR) | 0.001mm (10-6m) | seeing, photography, worldwide communication using optical fibres | burning, blindness if concentrated |
| Ultraviolet (UV) | gas discharge, very hot objects, UV lamps, sun | photographic film | 0.00001mm (10-8m) | sun-tan lamp, making ions, making vitamin D, water purification plants to kill bacteria | sunburn, skin cancer |
| X-rays | very fast electrons hitting a metal target | photographic film | 10-10m | imaging defects in bones, hidden devices | cell destruction, cell mutation, cancer |
| Gamma rays (\(\gamma\)) | radioactive nuclei decaying | photographic film, GM tube | 10-12m | medical tracers, killing cancerous cells, sterilisation | cell destruction, cell mutation, cancer |
| Type of wave | Radio: LW |
|---|---|
| Typical source | electronic circuits, stars and space |
| Example of detector | aerial and electronic circuit |
| Approximate wavelength | 1km |
| Typical users | communications, radio, TV |
| Dangers of over exposure | safe (unless very concentrated) |
| Type of wave | Radio: MW |
|---|---|
| Typical source | electronic circuits, stars and space |
| Example of detector | aerial and electronic circuit |
| Approximate wavelength | 100m |
| Typical users | communications, radio, TV |
| Dangers of over exposure | safe (unless very concentrated) |
| Type of wave | Radio: VHF |
|---|---|
| Typical source | electronic circuits, stars and space |
| Example of detector | aerial and electronic circuit |
| Approximate wavelength | 1m |
| Typical users | communications, radio, TV |
| Dangers of over exposure | safe (unless very concentrated) |
| Type of wave | Microwaves |
|---|---|
| Typical source | electronic circuits, cool objects |
| Example of detector | aerial and electronic circuit |
| Approximate wavelength | 1cm (10-2m) |
| Typical users | communications satellites, telephony, heating water and food |
| Dangers of over exposure | burning, if concentrated |
| Type of wave | Infra red (IR) |
|---|---|
| Typical source | electronic devices, warm objects, sun |
| Example of detector | electronic detectors, special photographic film, blackened thermometer |
| Approximate wavelength | 0.1mm (10-4m) |
| Typical users | magic eyes in security lighting, remote control (eg TV) |
| Dangers of over exposure | burning, if concentrated |
| Type of wave | Light; Red, Orange, Yellow, Green, Blue, Indigo, Violet |
|---|---|
| Typical source | electronic devices (LED), hot objects, sun |
| Example of detector | eye, photographic film, electronic devices (eg, LDR) |
| Approximate wavelength | 0.001mm (10-6m) |
| Typical users | seeing, photography, worldwide communication using optical fibres |
| Dangers of over exposure | burning, blindness if concentrated |
| Type of wave | Ultraviolet (UV) |
|---|---|
| Typical source | gas discharge, very hot objects, UV lamps, sun |
| Example of detector | photographic film |
| Approximate wavelength | 0.00001mm (10-8m) |
| Typical users | sun-tan lamp, making ions, making vitamin D, water purification plants to kill bacteria |
| Dangers of over exposure | sunburn, skin cancer |
| Type of wave | X-rays |
|---|---|
| Typical source | very fast electrons hitting a metal target |
| Example of detector | photographic film |
| Approximate wavelength | 10-10m |
| Typical users | imaging defects in bones, hidden devices |
| Dangers of over exposure | cell destruction, cell mutation, cancer |
| Type of wave | Gamma rays (\(\gamma\)) |
|---|---|
| Typical source | radioactive nuclei decaying |
| Example of detector | photographic film, GM tube |
| Approximate wavelength | 10-12m |
| Typical users | medical tracers, killing cancerous cells, sterilisation |
| Dangers of over exposure | cell destruction, cell mutation, cancer |