February 2008
Intermediate to advanced
192 pages
4h 1m
English
The verdict of history is unambiguous: Alexander Graham Bell invented "the telephone." Yet what did this really mean? What was it that he actually invented?
Bell's initial breakthrough was a telephone transmitter in which sound waves vibrated a diaphragm connected to a needle suspended in a high-resistance liquid. The vibration of the needle varied the amount of surface area of the needle in contact with the liquid, thereby varying the resistance and strength of the current passing through the circuit. This variation in electrical current represented the transformation of sound waves into electrical current, which could be reconverted into sound by his telephone receiver.
Bell's liquid transmitter worked, but ...