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Radiopresentation2 Radiopresentation2 Presentation Transcript

  • Radio waves
    • By Elmer George
  • What is a radio wave?
    • Radio waves are part of the electromagnetic spectrum which is a range of all frequencies of electromagnetic radiations.
    • Different frequency bands transmit radio waves differently.
    • They are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum.
    • Radio waves have frequencies from 300 GHz to as low as 3 kHz
    • They vary in wavelength from around a millimetre to 100,00 km
  • How does a radio wave work?
    • Radio waves are planned to reach local, regional, national and sometimes international areas.
    • AM radio waves use low frequency ground waves so that they can follow the curvature of the earth.
    • FM radio waves use direct waves that travel in straight lines, so they use radio transmitters for long distances.
    • Radio transmitters are electronic devices which with the use on antennas produce radio waves.
  • Electromagnetic spectrum.
    • Electromagnetic spectrum is a range of frequencies of electromagnetic radiation, it extends from a low frequency used for radio to gamma radiation.
    • The Electromagnetic spectrum consists of:
    • radio
    • infrared
    • ultraviolet
    • x-ray
    • gamma ray
  • Television
    • Television travels at the same speed of light roughly 300.000 km/s or 186.000 miles per second.
    • Television is a telecommunication medium for transmitting and receiving moving images, that can be black and white or in colour with or without sound.
    • They have been commercially available since the late 1920’s.
    • It has become a necessity in any household as it is a major tool used in advertising, a source of entertainment and news since the 1970’s.
    • DVD’s, Blue ray and video cassettes have made televisions frequently used for watching recorded and broadcast material.
    • Television recently has become available via the internet such as BBC iplayer and youtube.
  • Microwaves
    • Microwaves have a wave length that is short so it can be measured in centimetres.
    • Microwaves can also be used for transmitting information because they can penetrate light rain, haze, snow, clouds and smoke.
    • Microwaves are also used for radars, it was created to determine the range and detect objects by transmitting short bursts of microwaves, then the object is recorded.
  • Wi-Fi
    • Wifi is wireless networking, it gives you the ability to connect to a PC or network using a radio signal, it is perfect for home and office use.
    • Wifi comes in two speeds 802.11b this transfers data and 11 megabits per second and the more recent 801.11g which goes up to 54 megabits per second.
    • Compared to bluetooth wifi is much faster as bluetooth’s speed is 0.57 megabits per second.
    • wifi has a typical range of 500 feet indoors, laptops and even mobile phones come with wifi built in these days because of the growing use of it.
    • Wifi has become so common that it is offered in most public places even fast food restaurants for example mcdonalds.
  • Infrared Waves
    • Infrared waves are in between the visible and microwave part of the electromagnetic spectrum.
    • “ near infrared” light is closer in wave length to visible light, and “far infrared” is closer to the microwave part of the electromagnetic spectrum.
    • “ far infrared” waves produce heat, they are thermal so we feel this type if wave daily. for example sunlight, radiator and a fire.
    • “ near infrared” are shorter and do not produced any heat, they are the waves used by your television remote.
    • human’s produce infrared waves at normal body temperature.
  • Reference
    • - Radio wave information
    • - Infrared information
    • information - Wifi information
    • - Television information