Alessandro Volta

Alessandro Volta
Alessandro Volta
	File:Alex volta.jpg Alessandro Giuseppe Antonio Anastasio Volta (1745-1827)
Born	February 18 1745; Como, Lombardy, Italy
Died	March 5 1827; 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, he 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 he 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 dead 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. 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.)

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. This is how it works. The electrolyte exists in the form 2H⁺ and SO₄ ^2-. 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:

The zinc --------------Zn -> Zn²⁺ + 2e^-
The copper ----------Cu -> Cu²⁺ + 2e^-
The sulphuric acid --H₂SO₄ -> H₂ + SO₄

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.

Honors

In honor 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.

Volta is buried in the city of Como in Italy; the Tempio Voltiano near Lake Como 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.

Alessandro Giuseppe Antonio Anastasio Volta portrait.
Volta demonstrating his battery to Napoleon in 1801, by Giuseppe Bertini

Volta demonstrating his battery to Napoleon in 1801, by Giuseppe Bertini
Volta pile on exhibit in the Volta Temple, Como, Italy

Volta pile on exhibit in the Volta Temple, Como, Italy
Another Volta pile on exhibit in the Volta Temple, Como, Italy