6. Electromotive Force … the force which produces, or tends to produce, electricity, or an electric current; sometimes used to express the degree of electrification as equivalent to potential, or more properly difference of potential. This end has more conductance This side has some conductance, but not as much as the opposite end.
(Electricity from muscle or metal???)The year was 1780 and the region was Northern Italy. The hot topic, at least among the scientific community, was a little disagreement between Luigi Galvani, a professor of anatomy at the University of Bologna and Allesandro Volta, a physicist from Como. Galvani was especially interested in a phenomenon that he had recently observed in his laboratory. While dissecting a frog held by a brass hook, Galvani noticed that as he touched the nerve of the frog with his metal knife that the frog’s leg would twitch (note – he had been doing some experiments with static electricity and the knife most likely was charged). The connection for Galvani was that perhaps the source of electricity might be contained within the organism which led to his theory of “animal electricity”. This discovery ultimately led to discussions with Volta who was skeptical of Galvani’s theory. Through his experiments, Volta demonstrated that electricity did not come from animal tissue but rather that the twitching was a result of current generated from the contact of dissimilar metals and that the frog leg was only acting as a detector. Building upon this principle, Volta constructed the Voltaic Pile in 1800 by stacking round plates of copper and zinc separated by disks of cardboard moistened with salt solution; the forerunner to what would become one of the most useful technological discoveries of the time: “the battery”. To see what impact this new technological device had on the scientific community just travel down the timeline of later scientists and inventors such as Andre-Marie Ampere (electrodynamics), Hans Oersted (electromagnetism), Michael Faraday (electromagnetic induction), Samuel Morse ( telegraph), Thomas Edison (light bulb) and Shockley, Brattain & Bardeen (transistor). In the labs of each of these scientists or inventors the battery was the technological building block that enabled these persons in their discoveries of new electronics technology and theories of electricity. In fact, a study of the history of electricity shows that technology and science have long maintained an “enabling” relationship. The development of new technology has enabled scientists to continue their discoveries of electricity which in turn has led to the development of new electronic technologies such as the transformer, light bulb and electric motor which have in turn had a dramatic impact on the way we live.