FREE ESSAY ON RADIO

RADIO

HISTORY
Towards the end of the 19th century scientists were attempting to send messages over
distances without wires. They were not searching for a means of mass-communication, but
simply exploring the possibility of using electromagnetic waves in order to communicate
between two fixed points. 
There in no single inventor of radio, it came from several international developments.
The pioneers of radio studied the work of a British physicist James Clerk Maxwell, who
published his theory of electromagnetic waves in 1873. It was the German physicist
Heinrich Rudolf Hertz who first generated such waves electrically. Although, the waves he
came up with were unable to travel large distances. It was an Italian electrician and
inventor Guglielmo Marconi who succeeded in developing both a suitable receiver and an
improved spark oscillator, which was connected to an effective antenna to transmit radio
waves over significant distances. In 1896 Marconi transmitted signals for a distance
greater than 1.6 km. Within a year of his first demonstration he transmitted signals from
shore to a ship at sea 29 km away. In 1899 he established commercial communication
between England and France, and in 1901 he succeeded in sending a simple message across
the Atlantic. 
This was still only wireless transmission of signals rather than wireless transmission of
sound itself. On Christmas Eve in 1906 an American, Reginald Fessenden, managed to
transmit speech and music over several hundred miles out to sea. Over the next few years
other demonstrations followed in the United States, Britain, and Europe.
The combination of continuous signals being sent out from transmitters and more sensitive
receivers laid the technical basis for more wide-scale listening, but there was in the
years still little appreciation of the medium's social possibilities. Radio was thought
of private means of point-to-point communication, rather than public means of mass
communication.
The first significant users of radio coastal, marine, army, and intelligence services
were, however, content with this approach. Both British and Germans using radio to
communicate to naval forces from the outset, and governments commandeering all wireless
stations, seemed to entrench this pattern. World War 1 also motivated technical research.
In the interwar years, cinema and popular newspapers were already providing ever larger
numbers of people with entertainment and information on a national scale. Individuals
were being conceived in large numbers and this meant mass markets for all sorts of
consumer goods. So when the early wireless amateurs demanded something to listen to,
companies such as Marconi in Britain and the General Electric Company and Westinghouse in
America were keen to produce radio receivers.
The useful function involved in a radio is that you can tune your radio to a radio
station by using the control knob on the radio. On a standard radio there are two bands
you can switch to AM and FM. FM stands for frequency modulation, and AM stands for,
amplitude modulation. The difference between the two bands are the way they are
broadcasted. AM is being amplitude modulation the pitch of the radio waves are based on
the amplitude of the wave. So for example the higher the amplitude the higher the pitch
the radio will receive. As for FM because the waves aren't based on the amplitude they
are based on the frequency of the waves. So the more frequent the waves are the higher
the pitch of the sound.
A radio works by using an antenna, which intercepts part of the radio waves. A signal
voltage across the coil induces a voltage in the coil, the frequency (AM, FM) is then
chosen by the variable capacitor. The capacitor in my circuit is only tuned for AM. Then
the frequency comes out of the capacitor and into the transistor, which you use to tune
your radio to a station on that frequency.
The average electrical power used is: