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STORIES
OF INVENTIONS AND DISCOVERIES
Telephone
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Invented by: Alexander Graham Bell
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Nationality:
Scottish
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Date:
1876
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Alexander Graham
Bell was a doctor. He workea with deaf children
and understood the way sounds caused vibrations.
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While only in his
20's, he discovered a way of converting vibrations
into variations in electric current - and back again.
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His telephone had
a diaphragm (a thin metal sheet) which vibrated
when spoken to; close
behind the diaphragm was an electromagnet
which converted the
vibrations into electric signals.
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Bell's telephone
had a single transmitter receiver: when you had
finished speaking into
the microphone you held it to your ear and listened
to the other person's voice.
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In 1877, Thomas
Edison invented a better, separate, microphone
using carbon granules
behind the diaphragm. Apart from that, today's
telephone is as Bell
invented it.
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