The Electromagnetic Spectrum.

Radio Waves

Radio Waves are a type of electromagnetic wave and like all others travel at the speed of light. They occur naturally in our environment by lightning or some astronomical objects, we produce them with our mobile phones, radios, GPSs and many other electronic devices.

Microwaves

Microwaves have frequencies between 1010 and 1011 Hz, and have a wavelength of 10-2 to 10-3 , they are produced by microwaves, ovens and microwave transmitters and are detected by microwave receivers.  We use them in cooking foods, communication and radar so when you use a microwave you’re using microwaves or when you’re using a mobile phone you’re using microwaves.

Infrared

Infrared covers waves with wavelengths between 1mm to 50 nm and frequencies from 300GHz to 400 THz; however it can be split into three different parts:

• Far – Infrared            Wavelength: 1 mm -10 μm           Frequencies: 300 GHz – 30 THz
• Mid – Infrared           Wavelength: 10 μm - 2.5 μm           Frequencies:        30 THz - 120 THz
• Near – Infrared         Wavelength: 2500nm – 750nm           Frequencies: 120 THz – 400 THz

Your body detects infrared as heat, and so any objects that radiate heat is a source of Infrared, we use infrared in night vision, remote controls, infrared cookers and infrared heaters. If the human skin is exposed to excessive amounts of Infrared it may burn.

Visible

Visible light is the only light within the electromagnetic spectrum that we can actually see with our own eyes, if we could see infrared and ultraviolet light if we looked at a rainbow beyond the red part of the rainbow would be infrared and beyond the violet end would be ultraviolet. Visible light has a wavelength of between 380  and 760 nm and a frequency of about 790–400 terahertz. We use visible light to read barcodes, communication (across optical fibres) and to read compact discs. It can be detected by sensors inside digital cameras and our eyes.

Ultraviolet

Ultraviolet rays have a wavelength shorter than visible light but longer than X – Ray rays, their wavelength ranges from 10 - 400 nanometres. It is named ultraviolet because it has waves with frequencies higher than humans can distinguish as the colour violet, hence ultraviolet.  Some subtypes of ultraviolet light include black light, abbreviated to UVA, and germicidal UVC. It is mainly produced by the sun, and most of us are only aware of the fact that it causes sunburn. We use it for tanning and security markers.

X – Rays

X – Rays have wavelengths in between 10 and 0.01 nm, both gamma rays and x – rays are very similar so now anything with a higher frequency than 10−11 m is considered a gamma they ray and anything lower is an X – Ray. Wilhem Conrad Röntgen was the X- Rays discoverer, who discovered them in 1895; he named them X – Rays because he wasn’t sure what type of radiation they were. Most people know about them because of their medical use, for scanning fro broken/ fractured bones or to look for growing teeth. They are also known as Röntgen radiation, for obvious reasons.

Gamma Rays

Gamma Rays were discovered by Paul Villard in 1900, since then they have had multiple uses, some of these are:  They can be measured with extremely high accuracy using Compton scattering. A standard Gamma ray will normally have frequencies of more than 1019 Hz, and wavelengths smaller than 10 picometres. Gamma Rays are produced mainly when a nucleus emits an α or β particle, the daughter particle will split into a lower energy state and a gamma ray.  If your body is exposed to gamma rays they damage your cells, this can lead to mutation and finally cancer. We use gamma rays to sterilise food, medical equipment etc., and to treat cancer through chemotherapy.