Electromagnetic Spectrum Concepts of Health Physics
communicate waves
You should know some of the properties and uses of tuner waves. Radio waves ar made by various types of transmitter, depending on the wavelength. They argon also given off by stars, sparks and lightning, which is why you hear interference on your radio in a thunderstorm.
Television and radio
Radio waves have lower frequencies and longer wavelengths than microwaves. They be used to transmit television and radio programmes. Television uses higher(prenominal) frequencies than radio.
A radio programme suck upr does not require to be directly in view of the transmitter to receive programme signals. For low frequence radio waves diffraction can surrender them to be received behind hills, although repeater ranges are often used to improve the quality of the signals.
The lowest frequency radio waves are also reflected from an electrically charged level of the upper atmosphere, called the Ionosphere. This means that they can reach receivers that are not in the line of sight because of the curvature of the Earths surface.
[pic]
Microwaves and radio waves in the atmosphere
USE
Radio waves are the lowest frequencies in the electromagnetic spectrum, and are used mainly for communications.
Radio waves are divided into:-
[pic]Long Wave, close to 1~2 km in wavelength. The radio station Atlantic 252 broadcasts here.
[pic]Medium Wave, around 100m in wavelength, used by BBC Radio 5 and other AM stations.
[pic]VHF, which stands for Very High relative frequency and has wavelengths of around 2m. This is where you find stereo FM radio stations, such(prenominal) as BBC Radio 1and Further up the VHF stripes are civilian aircraft and taxis.
[pic]UHF stands for Ultra High Frequency, and has wavelengths of slight than a metre. Its used for Police radio communications, television transmissions and troops aircraft radios - although military communications are now mostly digital and encrypted.
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