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VOICE ONE:
This is Steve Ember.
VOICE TWO:
And this is Faith Lapidus with the VOA Special English programEXPLORATIONS. You are listening to our program today on a radio.Almost no communication would exist in the world without theelectromagnetic waves that make radio possible. Today we explain thehistory of radio and tell how it works.
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VOICE ONE:
Our story begins in Britain in eighteen-seventy-three. Ascientist named James Maxwell wrote a mathematical theory about akind of energy. He called this energy electromagnetic waves. Histheory said this kind of energy could pass unseen through the air.Mister Maxwell was not able to prove his idea. Other scientistscould not prove it either until German scientist Heinrich Hertztried an experiment in eighteen-eighty-seven.
VOICE TWO:
Mister Hertz’s experiment sounds very simple. He used two piecesof metal placed close together. He used electricity to make a sparkjump between the two pieces of metal.
He also built a simple receiver made of wire that was turned manytimes in a circle or looped. At the ends of the loop were smallpieces of metal separated by a tiny amount of space. This receiverwas placed several meters from the other device.
Mister Hertz proved that Mister Maxwell’s idea was correct.Electromagnetic waves or energy passed through the air from onedevice to the other.
VOICE ONE:
Later, Mister Hertz demonstrated the experiment to his studentsin a classroom. One of the students asked what use might be made ofthis discovery. But Mister Hertz thought his discovery was of nouse. He said it was interesting but had no value. He was wrong. Hisexperiment was the very beginning of every kind of electroniccommunications we use today. In recognition of his work, the unit offrequency of a radio wave, one cycle per second, is named the hertz.
VOICE TWO:
Radio waves became known toscientists as Hertzian Waves. But the experiment was still of no useuntil Guglielmo Marconi improved on the device that created HertzianWaves. He began his experiments in Italy in eighteen-ninety-four.
Mister Marconi was soon able to transmit sound across a distanceof several kilometers. He tried to interest Italian governmentofficials in his discovery, but they were not interested.
Mister Marconi traveled to Britain. His invention was wellreceived there. In eighteen-ninety-seven, he established theWireless Telegraph and Signal Company. The company opened theworld’s first radio factory in Chelmsford, England ineighteen-ninety-eight.
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VOICE ONE:
Very quickly, people began sending and receiving radio messagesacross long distances using equipment made by Mister Marconi’scompany.
Ships at sea needed the device. Before Mister Marconi’sinvention, they had no communication until they arrived in port.With radio, ships could call for help if they had trouble. Theycould send and receive information.
All of Mister Marconi’s radios communicated using Morse code. Itsounds like this. What you will hear are three letters. V-O-A. Wewill repeat, or send, each group of three letters two times.
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An expert with Morse code could send and receive thirty or fortywords a minute. Mister Marconi’s radio greatly increased the speedof communications.
VOICE TWO:
On December twenty-fourth, nineteen-oh-six, radio operators onships in the Atlantic Ocean near the American coast began hearingstrange things. At first it was violin music. Then they heard ahuman voice. The voice said “Have a Merry Christmas.”
That voice belonged to a man named Reginald Fessenden. He hadbeen working on producing a device that could transmit the humanvoice or music using radio. He decided to try it for the first timeon December twenty-fourth. It was the first time a human voice hadbeen heard on radio.
VOICE ONE:
Improvements in radio technology now came more quickly. Largecompanies became interested. Broadcasting equipment and radioreceivers were improved.
Fourteen years after Mister Fessenden’s voice was heard by radiooperators at sea, the first real radio broadcast was transmitted. Itcame from the city of Pittsburgh, Pennsylvania.
The radio program was transmitted on radio station K-D-K-A on theevening of November second, nineteen-twenty. The man speaking on theradio was Leo Rosenberg. He was announcing the early results of thepresidential election between James Cox and Warren Harding.
Within a year, the little radio station employed the world’sfirst full-time radio announcer. His name was Harold Arlin. K-D-K-Ain Pittsburgh is still a successful radio station today. Oh, andMister Harding won the presidential election!
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VOICE TWO:
Those first K-D-K-A broadcasts led to the success of the radioindustry. People began buying the first radios. Other companiesdecided radio could make a profit. Only four years after the firstK-D-K-A broadcast, there were six-hundred radio stations in theUnited States. Radio stations also began to broadcast in othercountries.
Radio stations began selling “air time” as a way to pay theirworkers and to pay for needed equipment. A few minutes of air timewere sold to different companies so they could tell about theirproducts to the radio station’s listeners. This method of supportingradio and later television is still used today.
VOICE ONE:
Radio changed the way people thought and lived. It permittedalmost everyone to hear news about important events at the sametime. Political candidates could be heard by millions of listeners.The same songs were heard across the country.
The work by British scientistJames Maxwell and German scientist Heinrich Hertz led to thedevelopment of modern communications technology. This includestelevision broadcasts, satellite use, cellular telephones,radio-controlled toys, and much more.
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VOICE TWO:
Now we will explain electromagnetic waves. We will begin withMister Hertz’s experiment. You can also try this experiment. It isvery easy to do. First, move the controls on your radio to an areawhere no station is being received.
Now, you will need a common nine-volt battery and a metal pieceof money. Hold the battery near the radio and hit the top of thebattery with the coin. You should hear a clicking noise on theradio.
Your coin and battery are a very simple radio transmitter. Thisradio will not transmit very far. However, if you know a little ofMorse code, you could communicate with this device.
VOICE ONE:
Electromagnetic energy travels almost like an ocean wave – up anddown, up and down. It also travels at the speed of light –two-hundred-ninety-nine-million-seven-hundred-ninety-two-thousand-four-hundred-fifty-eightmeters each second.
Scientists have learned how to separate radio waves intodifferent lengths called frequencies. This permits many radiostations to broadcast at the same time and not interfere with eachother.
Most radio frequencies around the world are named after HeinrichHertz. For example, one popular radio station in Washington, D-Cbroadcasts on six-hundred-thirty kilohertz. This is called a mediumwave. The kilo means thousand. The hertz means cycles or waves persecond.
VOICE TWO:
You may be hearing our broadcast on what is called short wave.These are frequencies between three-thousand andthirty-thousand-kilohertz. They are often called megahertz. Megameans a million. One megahertz is the same as one-thousandkilohertz.
Short wave is good for broadcasting very long distances. Theshort wave signals bounce off the ionosphere that surrounds theEarth, back to the ground and then back to the ionosphere.
Short wave can be heard for very long distances, but sometimesthe signal is not clear. However, radio technology continues toimprove. Today, V-O-A broadcasts to satellites in space that sendthe signal back to stations on the ground that transmit programswith a clear signal.
It is even possible today to use a computer to link withthousands of radio stations around the world. We think Mister Hertzwould be very proud of the little device he thought would never beof any use.
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VOICE ONE:
This program was written by Paul Thompson. It was produced byMario Ritter. This is Steve Ember.
VOICE TWO:
And this is Faith Lapidus. Join us again next week for anotherEXPLORATIONS program in Special English on the Voice of America.