Radio: A Form Of Communication
Mr. Zambizi
Physics
Radio is a form of communication in which intelligence is transmitted without
wires from one point to another by means of electromagnetic waves. Early forms
of communication over great distances were the telephone and the telegraph. They
required wires between the sender and receiver. Radio, on the other hand,
requires no such physical connection. It relies on the radiation of energy from
a transmitting antenna in the form of radio waves. These radio waves, traveling
at the speed of light (300,000 km/sec; 186,000 mi/sec), carry the information.
When the waves arrive at a receiving antenna, a small electrical voltage is
produced. After this voltage has been suitably ...
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wire that was not physically connected to the first.
Hans Christian Oersted had shown in 1820 that a current flowing in a wire sets
up a magnetic field around the wire. If the current is made to change and, in
particular, made to alternate (flow back and forth), the building up and
collapsing of the associated magnetic field induces a current in another
conductor placed in this changing magnetic field. This principle of
electromagnetic induction is well known in the application of transformers,
where an iron core is used to link the magnetic field of the first wire or coil
with a secondary coil. By this means voltages can be stepped up or down in value.
This process is usually carried out at low frequencies of 50 or 60 Hz (Hertz, or
cycles per second). Radio waves, on the other hand, consist of frequencies
between 30 kHz and 300 GHz.
In 1864, James Clerk Maxwell published his first paper that showed by
theoretical reasoning that an electrical disturbance that results from a ...
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(antenna) is increased.
The first wireless telegraph message across the English Channel was sent by
Marconi in March 1899. The use of radio for emergencies at sea was demonstrated
soon after by Marconi's wireless company. (Wireless sets had been installed in
lighthouses along the English coast, permitting communication with radios aboard
nearby ships.) The first transatlantic communication, which involved sending the
Morse-code signal for the letter s was sent, on Dec. 12, 1901, from Cornwall,
England, to Saint John's, Newfoundland, where Marconi had set up receiving
equipment.
The Electron Tube
Further advancement of radio was made possible by the development of the
electron tube. ...
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"Radio: A Form Of Communication." Essayworld.com. September 18, 2006. Accessed December 22, 2024. http://www.essayworld.com/essays/Radio-A-Form-Of-Communication/52581.
"Radio: A Form Of Communication." Essayworld.com. September 18, 2006. Accessed December 22, 2024. http://www.essayworld.com/essays/Radio-A-Form-Of-Communication/52581.
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