United States USA Date:1928 Duration:10 min 39 sec Sound:NO SOUND
Animated film shows how sound waves are created by the human voice cause movement of air molecules and how this movement is transmitted through the flexible diaphragm of the telephone mouthpiece. The electrons passing through carbon granules in the mouthpiece are transformed into electric current and the magnet and flexible diaphragm in the telephone receiver transforms the current into sound waves. An old man and a kid talking into phone.
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