Learn about The Telephone in this educational video from dizzo95.
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Male Speaker: The telephone now in use is similar to the device patterned it by "Alexander Graham Bell" though there have been many improvements; the basic principles are the same. In today's handset there is a micro phone in the mouth piece and a small loud speaker in the ear piece powered by an electrical circuit, when the vibrations of speech reach the diaphragm of the microphone it vibrates in turn. The diaphragm then causes the electrical current running through the microphone to vary and proportion to the sound. The resulting signal travels over a network, to the other phone at the receiving in the vibrations of speech are reproduced by another diaphragm, the electrical signal produced by the microphone, causes an electro magnets pole on a speaker diaphragm to vary with the same pattern, thus reproducing speech.