Misplaced Pages

Revision as of 00:47, 31 October 2007

Alessandro Volta
Alessandro Giuseppe Antonio Anastasio Volta (1745-1827)
Born	(1745-02-18)February 18, 1745 File:Como-Stemma.png Como, Lombardy, Italy
Died	March 5, 1827(1827-03-05) (aged 82) File:Como-Stemma.png Como, Lombardy, Italy
Nationality	Italian
Known for	Development of the electric battery
Scientific career
Fields	Physicist

Count Alessandro Giuseppe Antonio Anastasio Volta (February 18, 1745 - March 5, 1827) was an Italian physicist known especially for the development of the electric battery in 1800.

Career

In 1774, Volta became professor of physics in the Como high school. His passion had always been the study of electricity, and while still a young student he had even written a poem in Latin on this fascinating new discovery. His first scientific paper he titled De vi attractiva ignis electrici ac phaenomenis inde pendentibus

Inventions and discoveries

In 1775, Volta invented the electrophorus, a device that produced a static electric charge. In 1776-77 he studied the chemistry of gases, discovered methane, and devised experiments such as the ignition of gases by an electric spark in a closed vessel. Volta also studied what we now call capacitance, developing separate means to study both electrical potential V and charge Q, and to discovering that for a given object they are proportional. This may be called Volta's Law of Capacitance, and likely for this work the unit of electrical potential has been named the volt. In 1779 he became professor of experimental physics at the University of Pavia, a chair he occupied for almost 40 years. In 1794, Volta married the daughter of Count Ludovico Peregrini, Teresa, with whom he raised three sons. Each of his three sons went on to improve on the Voltaic Pile in ways that all ended in strait ends.

Around 1791 he began to study the "animal electricity" noted by Galvani when two different metals were connected in series with the frog's leg and to one another. He realized that the frog's leg served as both a conductor of electricity (we would now call it an electrolyte) and as a detector of electricity. He replaced the frog's leg by brine-soaked paper, and detected the flow of electricity by other means familiar to him from his previous studies of electricity. In this way he discovered the electrochemical series, and the law that the electromotive force (emf) of a galvanic cell, consisting of a pair of metal electrodes separated by electrolyte, is the difference of their two electrode potentials. That is, if the electrodes have emfs ${\displaystyle {\mathcal {E}}_{1,2}}$, then the net emf is ${\displaystyle {\mathcal {E}}_{2}-{\mathcal {E}}_{1}}$. (Thus, two identical electrodes and a common electrolyte give zero net emf.) This may be called Volta's Law of the electrochemical series.

In 1800, as the result of a professional disagreement over the galvanic response advocated by Luigi Galvani, he invented the voltaic pile, an early electric battery, which produced a steady electric current. Volta had determined that the most effective pair of dissimilar metals to produce electricity was zinc and silver. Initially he experimented with individual cells in series, each cell being a wine goblet filled with brine into which the two dissimilar electrodes were dipped. The electric pile replaced the goblets with cardboard soaked in brine. (The number of cells, and thus the voltage it could produce, was limited by the pressure, exerted by the upper cells, that would squeeze all of the brine out of the cardboard of the bottom cell.)

In announcing his discovery of the pile, Volta paid tribute to the influences of William Nicholson, Tiberius Cavallo and Abraham Bennet. he later discovered the volt

The Voltaic battery

The battery made by Volta is credited to have been the first cell. It consists of two electrodes: one made of zinc, the other of copper. The electrolyte is sulphuric acid. The electrolyte exists in the form 2H and SO₄ . The zinc, which is higher than both copper and hydrogen in the electrochemical series, reacts with the negatively charged sulphate. ( SO₄ ) The positively charged hydrogen bubbles start depositing around the copper and take away some of its electrons. This makes the zinc rod the negative electrode and the copper rod the positive electrode.

We now have 2 terminals, and the current will flow if we connect them. The reactions in this cell are as follows:

However, this cell also has some disadvantages. It is unsafe to handle, as sulphuric acid, even if dilute, is dangerous. Also, the potential difference in the terminals finishes after some time. So it is not durable, and therefore, not a suitable choice.

Honours

In honour of his work in the field of electricity, Napoleon made him a count in 1810; in 1815 the Emperor of Austria named him a professor of philosophy at Padua.

Before 1796, Lombardy was ruled by Austria. From 1796 to 1815, Lombardy came under Napoleon's rule. After 1815, Lombardy was once again under Austrian rule. Thus Volta was once a subject of the Emperor of Austria, later a subject of Napoleon and then later a subject of the Emperor of Austria again.

He was a long-time correspondent of the Royal Society and was made a fellow (FRS). He received the Society's 1794 Copley Medal. He published his invention of the Voltaic pile battery in 1800 in the Philosophical Transactions of the Royal Society. He was in correspondence with scientists in Austria, which ruled Lombardy in his day, and inm France: in fact his 1800 paper was written in French.

Volta is buried in the city of Como; the Tempio Voltiano near Lake Como there is a museum devoted to explaining his work; his original instruments and papers are on display there. The building appeared, along with his portrait, on Italian 10.000 lira banknote, before the introduction of the euro.

In 1881 an important electrical unit, the volt, was named in his honor. The Toyota Alessandro Volta is named after Volta. Volta Crater on the Moon is also named after him.

Retirement

Volta entered retirement in Spain.

References

1. *Elliott, P. (1999). "Abraham Bennet F.R.S. (1749-1799): a provincial electrician in eighteenth-century England" (PDF). Notes and Records of the Royal Society of London. 53(1): 59–78. (
2. Giuliano Pancaldi, "Volta: Science and culture in the age of enlightenment", Princeton University Press, 2003.

External links

• Alessandro Volta on the 10000 Italian Lire banknote.
• Catholic Encyclopedia article on Alessando Volta.
• ItalianVisits.com - Como, Volta's birthplace

Template:Persondata

• 1745 births
• 1827 deaths
• People from Como
• Italian physicists
• History of neuroscience
• Italian inventors
• People associated with electricity
• Scientific instrument makers