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Figure 1: Allesandro Volta
We’ve been taking a break from hard-hitting mechanical engineering and materials science blogs with some pieces on the Italian masters of science, mathematics and engineering in the 16-19th centuries. I’ve previously explored the lives and contributions of Evangelista Torricelli, Giovanni Venturi and Giovanni Cassini. For this blog, I’m focusing on Alessandro Volta, who helped revolutionize our understanding of electricity and electrochemstry it in the late 18th century.
Alessandro Volta (1745-1827)
Alessandro Volta was born in 1745 in Como, near the modern border to Switzerland. Volta was fascinated with electricity since the start of his scientific education, and his first published paper at the age of 24 was De Vi Attractiva Ignis Electrici (“On the Attractive Force of Electric Fire”). The Royal School in Como appointed Volta as a professor of physics in 1774, during which time he studied chemistry as well as electricity, managing to isolate and electrically-ignite methane gas. Five years later the centuries-old University of Pavia appointed him to the Chair of Experimental Physics, a position which he held for 40 years until his retirement. Volta was widely respected across the scientific community of Europe, and even earned the lasting admiration of Napoleon Bonaparte himself.
Electrical Engineering and Material Science
Figure 2: Illustration of Voltaic Piles from Volta’s publication “On the Electricity Excited by the Mere contact of Conducting Substances of Different Kinds”
As you might have guessed from his name, Volta had a big impact on the study of electricity. Volta was one of many scientists experimenting with electricity at the time, including Benjamin Franklin and Volta’s local Bolognese rival Luigi Galvani (from whom we coined the term “galvanic”). Volta’s early work traced the same lines of thinking as others; his 1775 invention of a static-electricity-generating “electrophorus”, for instance, was pre-empted by a similar machine patented in 1762. Volta’s true breakthrough into the annals of history came after observing Galvani’s 1791 experiments in making frogs’ legs twitch with the application of two different types of metals. Galvani hypothesized that the leg contained a unique “animal electricity”, generated by an internal organ and carried to the muscles through a fluid in the nerves. Galvani theorized that the two different metals were inspiring that fluid to flow, thus making the leg twitch. Volta was not convinced that this electricity in the frog leg was a different phenomenon than other types of electricity that had been observed, however. So, he set about recreating Galvani’s results with a piece of brine-soaked paper instead of dismemebered legs, taking animals out of the equation.
This simple experiment set the stage for a number of electrical breakthroughts. During his experimentation, Volta discovered that the amount of electricity generated varied based on which two metals he used to touch the paper. Zinc and copper showed a higher “electromotive force” than tin and iron did, for instance. Using his observations, he assembled the first chart of electrode potentials, an expanded version of which is still studied today in chemistry, electrical engineering andmaterials science classes. The list shows the voltage potential of a number of electrochemical reactions, and can be read as follows:
- The higher the electrode potential, the more an element wants to accept negatively-charged electrons to reduce its charge (called reduction)
- The lower the electrode potential, the more an element wants to raise its charge by losing electrons (calledoxidation)
- When in contact, the element with the lower electrode potential (the anode) will transfer its electrons to the element with higher electrode potential (the cathode)
- The further apart the anode and cathode are, the more voltage the reaction generates
With this chart in mind, Volta created the first modern battery, which he called an “electric pile”. He stacked pairs of zinc and copper disks, separated by slips of brine-soaked paper, and proved that an electric current flowed through a wire connecting the top of the pile to the bottom, as shown in Figure 3. We use the same chart today to develop and calculate the effectiveness of batteries…consider the nickel-cadmium (NiCd) rechargeable batteries that are common these days. Volta’s easy-to-create and reliable battery was crucial to the study of electricity and electrochemistry. When faced with naming the SI (metric system) unit of electric potential and electromotive force, the scientific community easily decided on the “Volt”.
Figure 3: Volta’s electric pile
Borbrav, “Voltaic Pile” / GNU Free Documentation License
If you want a great illustration of how electrochemical reactions work, check out this Crash Course.
Lasting Impact
Volta’s battery absolutely revolutionized the world of technology, providing scientists and inventors with a simple and reliable source of electricity. Furthermore, his research into the chemistry and material science behind the electrochemical reactions of materials caused an explosion of progress in electrical research. Between the battery’s invention in 1800 and Volta’s death in 1827, scientists had decomposed water into hydrogen and oxygen, discovered seven new elements, and begun investigating the link between electricity and magnetism. Using Volta’s work, Daniel Faraday created the first electromagnetic motor in 1821, and Volta barely missed Anyos Jedlik’s creation of the first practical DC motor in 1828. An electrical engineer and chemist ahead of his time, Volta would no doubt be both astounded and fascinated by modern products of the electrical revolution he helped spark.
References
“Alessandro Volta.” Famous Scientists. famousscientists.org. 28 Jul. 2014. Web. 1/13/2016 <http://www.famousscientists.org/alessandro-volta/>.
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